Elemental mercury removal using a wet scrubber

摘要

Mercury (Hg) is a toxic metal that is emitted into the environment by both211u001enatural and human activities. Acute and chronic exposure to mercury and methyl 211u001emercury in humans results in central nervous system damage, kidney damage, and 211u001eeven death. Although some Hg emission sources have been regulated, coal-fired 211u001eutilities have not been. In anticipation of federal regulations on mercury 211u001eemissions from coal-fired power plants, Argonne National Laboratory (ANL) has 211u001edesigned a flue gas simulation system to study the removal of elemental mercury. 211u001eThe simulated flue gas enters the system and combines with the inlet mercury 211u001evapor (from a calibrated permeation tube), carried by nitrogen gas. This combined 211u001egas continues past the flow meter and the pressure gage to the reactor inlet. 211u001eInside the reactor chamber, the flue gas is sprayed with NOXSORB(reg-sign), a 211u001echloric acid solution, which reacts with elemental mercury. The amount of 211u001ereaction (oxidation) of elemental mercury is important since mercury in an 211u001eoxidized form is highly soluble, In this form, the Hg can be picked up downstream 211u001eby a wet scrubber from fossil-fuel burning utilities. Experiments on mercury 211u001eremoval from flue gases have been conducted at ANL, with the participation of a 211u001esenior design team from Purdue University Calumet. Temperature variations ranging 211u001efrom room temperature to 350 F have been studied. Other parameters, such as the 211u001econcentration of NOXSORB(reg-sign), were also tested. Furthermore, pump speed and 211u001esprayer droplet sizes of the NOXSORB(reg-sign) solution were studied. A 211u001eliterature survey on the current and proposed mercury control legislation, along 211u001ewith the existing control technologies, has been performed as part of the senior 211u001edesign project. With guidance from ANL, an understanding of the simulation system 211u001ehas been developed. This information has been used to determine the mass 211u001etransfer. Another literature survey was performed on the reaction kinetics of 211u001emercury. The information obtained was used to postulate probable behavior of 211u001eelemental mercury in flue gas. The experimental results obtained at Argonne will 211u001ebe related to existing wet scrubber technology to determine the economic 211u001efeasibility of mercury removal. A cost per pound of mercury analysis will be 211u001eutilized.