5-07-09

Lots of Progress on removing SO₃ say Hot Topic Speakers

Yesterday there were excellent presentations and discussions in a 3-hour webinar on SO₃issues. The conclusion is that removing SO₃ down to well below 10 ppm is achievable at a reasonable cost. The nine speakers were experts on the subject.

Yougen Kong, Technical Development Manager, Solvay Chemicals Inc.

Keith Day, Business Development related to Dry Sorbent Injection, O'Brien & Gere

Geoff Urwin, Proposal Manager with Clyde Bergemann EEC

Edward V. Bowes, Manager, Fossil & Hydro Engineering, Dominion Resources, and Amy Evans, Marsulex

James "Buzz" Reynolds, Vice-Pres./Wet ESP, Siemens Energy, Inc.

John C. Caine, General Manager, Southern Environmental, Inc/ SEI

Kevin Dougherty, V.P., FuelTech

Dave Escott, Power Market Manager, FLSmidth

Trona and hydrated lime both have advantages. In some cases it makes sense to add Trona prior to the air heater and then lime prior to the wet FGD. Advantages of dry injection include mercury as well as SO₃ removal.

Ground limestone added at the air preheater is another successful approach which has proved its operational reliability. The effectiveness of removal is a function of temperature reduction across the air heater. Dominion Resources takes advantage of the higher boiler efficiency but is able to raise the air heater exit temperature if there is a failure in the injection system. CO₂ reduction and boiler efficiency improvement are proportional. So the ability to improve efficiency without corroding air heater exit ducts is an advantage

There were good questions and information provided by the participants. Peter Stromberg of Babcock Power pointed out that while there was lots of research on SO₂ removal with dry sorbent injection there was little data on SO₃ removal. He pointed out that much of the reaction is between H₂SO₄ liquid and the sorbent and not between the SO₃ gas and the sorbent.

The systems to deliver and uniformly distribute sorbent in the flue gas have been made much more reliable. Pneumatic transport of Trona requires gas conditioning. Hydrated lime can build up in areas where there is a pressure change.

Magnesium hydroxide can not only capture SO₃but can improve boiler efficiency and reduce the popcorn ash pluggage of the screens protecting the SCR catalyst.

Wet precipitators have a higher capital cost but lower operating costs. They also capture heavy metals. With MACT rules for toxics in the offing there will be considerable value attached to this capability. CO₂ capture systems cannot tolerate particulate or acid gases. So the WESP will be of particular interest for a utility ultimately contemplating CO₂ capture.

The bios and abstracts can be viewed as follows: May 7, 2009 Bios, Abstracts, Photos - Hot Topic Hour.htm

The power points are in the FGD Decision Tree and can be viewed as follows:

Yougen Kong – Solvay Chemicals

Start

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Scrub

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Physical

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Multi-pollutant Requirements

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Gases