MEMORANDUM

TO: Portland Cement NSPS Docket

FROM: Keith Barnett, USEPA/OAQPS/SPPD/MMG

DATE: October 16, 2007

SUBJECT: October 15, 2007, Meeting between US Environmental Protection Agency (EPA) and Mr. Peter Paone of FL Smidth Inc.

Introduction and Objectives

The purpose of the meeting was to obtain info rmation on the cement kiln design factors that result in low nitrogen oxide (NOx) a nd carbon monoxide (CO) emissions. Most of the information discussed in the meeting is included in the presentation attached to these meeting notes.

Meeting Participants

Keith Barnett, USEPA Mike Laney, RTI (contractor to EPA) Peter Paone, FL Smidth, Inc.

Information discusse d in the Meeting

FL Smidth is building the kiln for Drake cement in AZ and GCC in Pueblo CO. They are currently looking at mercury and tota l hydrocarbon abatem ent technology.

There are two types of raw mill – vertical and ball mills. Vertical grinding is 50 percent more efficient that ball mill grinding.

Loss on ignition in a cement k iln is 35 percent, mostly CO 2 . About 2-5 percent of the

CO 2 is left in the limestone after the calciner.

Tertiary Air – air from the clinker cooler returned to calciner Primary air – burner air – this is the smallest air flow Secondary Air – clinker cool er air to kiln th at enters under th e clinker cooler

Types of NOx

Feed NOx – negligible Thermal NOx – formed in kiln, much larger amount, not formed in calciner, need

at least 1300 o C.Fuel NOx – formed primarily in calciner Cement kiln NOx is primarily NO (98 percent on average)

Factor affecting formation of thermal NOx

Max theoretical flame temperature

Excess air rate Maximum materials temperature (burnibility) Flame shape (burner type)

One percent or less of free lime left in clinker

Hard materials require more heat to react

The FL Smidth kiln burner has a small air a nnulus, shaping swirl air and axial air. The burner pipe length is 8 – 12 mete rs, maybe 1 meter in diameter.

Their adjustments, how far the burner goes (in or out), swirl air, axial air.

Factor that affect fuel NOx (calciner)

Fuel nitrogen content Calciner design Temperature inside calciner

There is a NOx reduction reaction that take s place in the calciner that reduces NOx formed in the rotary part of the kiln. This reaction is favored at higher calciner

temperatures.

Factor affecting CO emissions

Calciner Fuel type

Fuel fines

Retention time Calciner design

Raw Materials Organics in the raw materials Addition of fly/bottom ask (due to carbon in these materials)

CO emissions can be as low as 0.5 lb CO/ton clinker with low excess air, and can be as high as 2-3 lb/ton clinker.

23 About 95 percent of the FL Smidth calciners are the ILC design. In the SLC-D they add a precombustion chamber to the ILC. The SLC-D is for low volatile fuels and waste

fuels.

In their designs they try to produce a reduci ng condition at the bottom of the calciner to reduce NOx. Feed a low percentage of meal at the bottom (15 percent) and the rest at point(s) higher in the calciner. Tertia ry air is used to complete combustion.

The calciner temperature is limited to 1100 o C to prevent materials from getting sticky.

Retention time 0.1 to 0.15 seconds.

Increased retention time and hot zones lower CO.

From a NOx perspective petroleum coke is not a good precalciner fuel, but it is a good

kiln fuel.

Florida has a lot of problems with burnability because they have a lot if easy grinding limestone mixed with hard quartz, and high volatile coal.

You need volatile coal and low nitrogen fuel to meet 1.95 lb/ton cli nker in the long term without SNCR. If burring 100 percent pet coke you can get 2.8 – 3.3 lb NOx /ton clinker. The fineness of the pet coke is a big factor.

SNCR does not increase CO emissions in FL Smidth systems.

Lower NOx emissions prior to the SN CR system reduce SNCR system costs.

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