6-04-09

Mercury Regulations and Technology was the Hot Topic Hour Yesterday

One hundred participants heard the latest on mercury technology and regulations in the June 4 Hot Topic Hour. The clear message from the session is that each utility power plant will have to meet a MACT standard which will likely be output-based rather than a percentage. The earliest compliance date is 2013. This could create a famine-feast sequence for suppliers. On the other hand, some states are moving forward. So 100 systems specifically for mercury removal are on order or installed.

Nick Hutson, Ph.D., Research Engineer, U.S. EPA Air Pollution Prevention & Control Division Office of Research & Development in Research Triangle Park, NC, explained that he is involved in mercury research projects including comparison of alternative sorbents. He does not represent the regulatory branch but did provide a good summary of the regulation status. Utilities are likely to face MACT regulations which will probably be output-based rather than a percentage reduction.

Nick discussed some work on the design of a multi-pollutant scrubber. In the question and answer period there was coverage of the potential for a two-stage scrubbing system in which the first stage captures HCl and makes 30 percent hydrochloric acid. Here is a link to the data on this approach in the FGD Decision Tree.

►

Scrub

►

Physical

►

Multi-pollutant Requirements

►

Gases

►

HCl

FGD Continuing Decision Process For: HCl

Incinerator plants in Europe are using chloride prescrubber technology. Mercury removal in excess of 99 percent has been confirmed by Vosteen.

http://www.mcilvainecompany.com/FGD_Decision_Tree/subscriber/Tree/DescriptionTextLinks/HCl Pre-scrubber Can Achieve More Than 99 Percent Mercury Removal.htm

Making hydrochloric acid as a by-product is very green and cost effective. Here is a feature article by McIlvaine in July 2007 Power Engineering on this subject.

http://www.mcilvainecompany.com/FGD_Decision_Tree/subscriber/Tree/DescriptionTextLinks/byproducts_can_make_coal_plants.htm

The pre-scrubber design recirculates a solution which starts with water and as the concentration of hydrochloric acid reaches equilibrium, the 30 percent grade acid can be bled from the loop. Part of this bleed stream can be reinjected prior to the SCR to ensure complete mercury oxidation. Here is the flow diagram.

http://www.mcilvainecompany.com/FGD_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Hydrochloric_Acid_Production_Schematic.doc

Removing the mercury from the acid can be accomplished with ion exchange resins. Bayer makes a resin which is used for this purpose and has been applied at waste incinerators in Europe.

http://www.mcilvainecompany.com/FGD_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Removal_Heavy_Metals.pdf

Dow Chemical has a patent for drying the hydrochloric acid following incineration of the wastes and then capture of the HCl in a chloride pre-scrubber followed by acid purification for metal removal by ion exchange.

http://www.freepatentsonline.com/20020114758.html

Two diagrams displayed during the session are not yet in the Decision Tree so we are providing the following links.

Schematic of the AEE System.

Schematic Wet HCl Scrubber HTH 6-4.doc

Description of the Von Roll system which makes commercial hydrochloric acid at Nuremberg.

Nuremberg Waste Incineration Plant - HTH 6-4.pdf

Karen E. Burchardt, Senior Environmental Engineer Energy Division of Burns & McDonnell, addressed common questions that electric utilities have regarding mercury control. She addressed regulations, ACI performance, ash impacts and water quality concerns. She responded to a specific question with the answer that many power plants will utilize a combination of means to reduce mercury

Dr. Constance (Connie) L. Senior, Manager Engineering Research and Development, Reaction Engineering International -

The addition of FGD systems, SCR, ACI to capture mercury, SO₂, and other pollutants will shift mercury from the stack gas to flyash, FGD gypsum and other air pollution control residues. This may have a significant impact on flyash production and quality. Flyash in landfills will generally not only retain mercury but absorb additional mercury if encountered.

George Offen, Senior Technical Executive EPRI, reviewed some of their projects including one evaluating the addition of activated carbon to the FGD recycle system. The challenge will be to separate the carbon from the gypsum.

John David, AQCS Mercury Control Babcock & Wilcox Company. His power points covering additives used in conjunction with FGD systems to capture mercury are posted but he was not a speaker due to a schedule conflict.

Paul S. Farber, PE DEE, Sargent & Lundy LLC, emphasized the importance of metals and HAPS other than mercury which will likely need to be removed. Connie had previously discussed the ability of ACI to remove selenium. The topic of HAPS was raised throughout the two-hour discussion.

Jean Bustard, ADA-ES described work on new flue gas conditioning agents which would replace SO₃. This would solve the dilemma of mercury removal at plants which are using FGC. Jean also confirmed that their 150 million lb/yr ACI plant will be up and running by mid 2010. Pictures showing a number of structures in place were proof of the progress.

The bios, abstracts and photos can be viewed as follows: June 4, Bios, Abstracts & Photos.htm

The individual slides are in the Mercury Decision Tree and can be viewed as follows:

**EPRI slides are not available at this time.

Dr. Constance Senior – Reaction Engineering

Start

►

Remove

►

Physical

►

Coal Combustion Byproducts - Risks

Mercury Continuing Decision Process For: Coal Combustion Byproducts - Risks