July 5, 2007

The Hot Topic Hour held July 5 on limestone size reduction included some amazing statistics. The milling market has been a steady $100 million dollar business up until the last few years. Orders in 2006 were $1 billion according to Randy Will of Metso.

Randy was one of three presenters. Others were Anthony Filidore of FL Smidth/FFE Minerals and Bob Sommerlad of Loesche. Bob led off with a presentation on dry grinding and the operational advantages. The other two presenters contended that while dry grinding was logical for dry scrubbing it does not make sense to dry limestone and then use it in a slurry. They further indicated that most limestone is wet enough when quarried that it must be dried prior to dry grinding. On the other hand it can be used directly in wet ball mills or vertical mills.

If there were to be regional grinding facilities as found in Europe and Japan then dry grinding makes sense. One interesting alternative is to utilize powdered limestone as a backup to the ball mill. Instead of purchasing a completely redundant mill, the utility can arrange for dry storage of enough limestone to operate while the ball mill is being repaired.

Anthony reviewed the extensive experience of FL Smidth/FFE Minerals in wet grinding and indicated that delivery times are now around 80 weeks, up from 50 weeks a few years ago.

Randy attributed much of the big increase in demand to mining industry expansions. These require the larger mills. Mills for FGD are smaller. There are a number of advantages to vertical mills but they do require a preliminary crushing phase whereas the ball mills can handle stone up to 1-1/2 inches.

One of the utilities sought further information on control and a discussion ensued relative to level control or use of the pump pressure at the hydrocyclone. With a variable speed drive it is possible to maintain a constant pressure at the hydrocyclone. This is a good indicator of particle separation even as the pump and hydrocyclone wear. The control philosophy is dependent on the overall decision as to whether to operate the plant over a range of capacities or just at one setting.

Due to the July 4^th holiday the FFE and Loesche presentations were made from the presenters’ desktops and not from our Decision Tree. However, we will add their presentations to the Decision Tree as soon as we receive them.

The Metso presentation is already in the FGD Decision Tree and can be accessed through the following link.

Metso Minerals – Randy Will

“Hot Topic” Webinars on Measurement of Mercury SO₃, Ammonia Slip, NO_x, July 12

There are so many developments on Mercury CEMS that we have added an afternoon “Hot Topic Hour” on July 12 to cover the developments. This is in addition to our long scheduled morning discussion on measurement of SO₃, ammonia slip and low level NO_x.

Three challenges for the CEM supplier industry are measurement of ammonia slip, SO₃ and NO_x at very low levels.  What continuous SO₃ measurement is necessary to control flow of removal additives?  Can NO_x analyzers accurately measure the 0.07 lbs/MMBtu or less that represents the limit in many permits? What are the cost and reliability of CEMS for these applications?  Ammonia slip causes opacity problems and pluggage of air heaters. Can you accurately measure and therefore control it?

At 9:00 a.m. CDT on July 12 there will be a 1-2 hour discussion of these issues. Then at 1:00 p.m. CDT we will re-convene to discuss the mercury measurement issues.

EPA has released "draft" method 30A and 30B which represent the instrumental analyzer and sorbent trap methods for doing RATA. How comfortable is the industry with these draft methods?

Now the NIST certification protocol for mercury calibrators (elemental and oxidized) is being worked on. Where does this process stand?

There are still questions on obtaining accurate measurement with the CEMS systems including probe plugging, sample transport and conversion of oxidized to elemental mercury. We will hear from the system integrators and instrument suppliers about these issues.

We have now conducted several “Hot Topic Hours” on mercury CEMS.  So this one will build upon the others and utilize the extensive information in the McIlvaine Mercury Decision Tree.