December 1 8 , 2015

EPA Docket Center WJC West Building Environmental Protection Agency Mailcode 2822 1 T 1200 Pennsylvania Ave., NW Washington, DC 20460

RE: Docket ID No. EPA

– HQ

– OAR

– 20 15

- 0 341 , Notice of Availability of the Environmental Protection Agency’s Update of Two Chapters in the EPA Air Pollution Control Cost Manual (80 Fed. Reg. 33515 ( June 12
, 2015))

The Institute of Clean Air Companies (ICAC) is submit ting comments in response to the October 21, 2015 letter from Mr. Larry Sorrels. The questions from the October 21 letter are restated along with the ICAC responses for each item.

Section 1.2.4 SNCR System : ICAC noted that this section was out of date and could provide input for making revisions. We invite you to offer material suitable for a rewritten draft of the revised section, or a written statement of what the SNCR background section should include.
ICAC Response: In general the section provides a good general description of an SNCR System. However, there are different configurations provided by individual SNCR providers that may utilize different approaches. There a re several paragraphs noted below that have been redlined to show the suggested changes to this section.

A. The first paragraph of Section 1.2.4 on Page 1

- 20 should be modified as follows:

There are were two original basic designs for the application of SNCR. The first is was an ammonia based system known as Thermal DeNOx that was developed and patented by Exxo n Research and Engineering Company in 1975. The second system was developed and patented by the Electric Power Research Institute (EPRI) in 1980. It is a

urea

- based process known by the trade name NOx OUT. The technology was originally
licensed to Fuel Tec h, which holds held several additional patents that claim ed improvements and enhancements to the basic process. Since that time, there have been a number of variations and improvements to the urea SNCR process, which are noted earlier in Section 1.2. F uel Tech has several sub

- licensees authorized to supply and install SNCR technology in several industrial sectors.
An SNCR system has four basic steps to accomplish:2

 Receiving and storing the reagent;

 Diluting, metering, and mixing the reagent;

 Injecting diluted reagent at appropriate locations in the boiler; and

 Mixing the reagent with flue gas.

These steps are common to both urea and ammonia SNCR; however, the design and equipment specifications for the two systems are different, because anh ydrous
ammonia based systems use the injection of is injected as a vapor while urea is injected as an aqueous solution. Aqueous ammonia based SNCR systems are very similar to aqueous urea systems in terms of the overall system approach of injecting a solut ion, and therefore are similar in terms of equipment

. Anhydrous and aqueous a mmonia based systems can be effective on units where the injection temperatures are in the range of 1600

- 1800F. However, U u rea is typically used in large boiler applications of SNCR because it is safer to store

, and has better dispersion properties , and can use urea droplet evaporation for effective injection at much higher temperatures found in utility furnace applications. Ammonia based systems have been effective on industrial
boilers and some fluidized bed utility boilers , but urea is the dominant reagent for utility furnace applications.

. A discussion of the SNCR equipment is given below. Figure 1.9 presents a simplified system flow schematic and Table 1.5 lists t he equipment requirements for urea

- based SNCR.

B. Second bullet on Page 1

- 24 under the heading of Injectors

 Wall injectors are attached to the inner wall of the boiler at specified locations. There is generally one nozzle for each injector location. Wall inje ctors are used in smaller boilers and urea based systems, where short

- range injection is sufficient to mix the reagent with the flue gas. They have a longer operating life than lance injectors because they are not directly exposed to hot flue gas. Wall in jectors
can either be use air or mechanical atomization prior to injection.

C. Last paragraph of Section 1.2.4, Page 1

- 25
The reagent injection systems used for anhydrous ammonia

- based systems are generally more complicated and expensive than those used in u rea

- based systems [29]. These systems inject gas

- phase ammonia rather than an aqueous solution. For this

reason, anhydrous ammonia

- based systems often use high

- energy lance systems with multiple injectors. The lances are placed in a grid formation across t he width and height of the boiler passes.3

Figure 1.10, Approximate NSR Estimation for Urea : ICAC noted it could share more recent data related to the relationship between NSR and desired NOx reduction, particularly for inlet NOx concentrations below 0.5 lb/MMBtu. We are interested in receiving the data that is referred to in this comment.
ICAC Respo nse: After reviewing Figure 1.10 , ICAC would recommend using the urea utilization calculation from Page 4 of the final version of the IPM Model

– Updates to Cost and Performance for APC Technologies SNCR Cost Development Methodology

, dated March 2013, which was prepared by Sargent and Lundy with funding from EPA , a copy of which is attached for convenience . We believe that this general calculation provides a good estimating tool for urea utilization. T here are a number of parameters
whic h affect actual utilization including boiler geometry, furnace temperatures, residence time, and combustion conditions. An estimate on a case by case basis by an experienced technology provider is suggested beyond the b asic tool used in the IPM model, which is based on more recent information than Figure 1.10.

Thank you for your consideration of these comments. Please feel free to contact Haley Armstrong , ICAC

, at ( 202) 478

- 6188 if you have questions or need more information.

Sincerely,

Betsy Natz ICAC Executive Director

cc: L. Sorrels , EPA