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### Icenhour, Melissa K.

From: Jerry Davis [JDavis@lsb-okc.com]

Sent: Thursday, July 28, 2011 1:52 PM

To: Bill Neuffer; John Carver

Cc: Ravi Srivastava; Icenhour, Melissa K.; Neulicht, Roy Subject: RE: SCR heatup during SSM conditions - Nitric Acid Baytown plant

Bill,

Good to hear from you and hope your team are doing well.

I have to be somewhat careful with your question to make sure I do not mislead you and provide information that could be misinterpreted.

In your inquiry there are specific words that really influence the answer

- those are "new nitric acid plant", "your method" and "preheating the SCR". So I want to be carefu l about giving a one word answer.

* "Preheating SCR"

-

o Preheating the SCR is one thing, but it does not alone mean that a plant could startup colorless or within a low NOx limit. Without sufficient pressure in the absorber column, a startup process could very likely overwhelm even a preheated SCR with NOx gas such that the SCR exit would still have high NOx values. So, if I say yes the SCR could be preheated, I am not saying that it would alone provide colorless/ low NOx startups.

o P reheating indicates your question is about startups only and not all "SSM's". It is certainly easier to design a SCR preheater for a known startup process than to be able to assure the SCR (with or without a preheater) could control NOx during a malfuncti on. o Some plants for various reasons have SCRs that have a higher minimum reaction temperature. The higher the minimum temperature requirement, the more difficult this preheating would be. We can just barely get the SCR hot enough to achieve minim um required reaction temperature for our startups with the 600 psig steam available from Bayer. Many sites do not have steam at this high of pressure and thus may not have high enough steam temperature for the SCR catalyst to achieve minimum reaction temp erature at initial start

- up.

"Your Method"

-

o Our method is to use steam from Bayer and I would say that not all plants or new plants will have this advantage. * However, with a new plant, the design could use a different method to achieve preheating. I am not sure of other methods that have been proven in our industry or their net effect on other issues such as green house gas emissions, but conceivably di rect fired gas
heaters, hot oil heaters, electric heaters, or a small steam boiler could be installed specifically for nitric acid start

- up. These options are almost certainly more expensive vs our situation where steam is simply available by opening a va lve connected to the site steam distribution header. Cost vs benefit analysis would be required to evaluate a specific proposal

* "new nitric acid plant"

-

o In a new plant, some additional emission control features may be designed into it at a cost. However, if the site does not have steam available, then the cost goes way up. And unless the infrastructure allows, the additional features may reduce emissions during startup, but still not make it possible to stay below very low limits.2 Ho pe this helps,

Jerry

----- Original Message

----- From: Bill Neuffer [mailto:Neuffer.Bill@epamail.epa.gov] Sent: Wednesday, July 20, 2011 8:11 AM To: Jerry Davis; John Carver Cc: Ravi Srivastava; Icenhour, Melissa K.; Neulicht, Roy Subject: SCR heatup duri ng SSM conditions

- Nitric Acid Baytown plant

John, Jerry;

As noted on p.9 of the ICR you completed for the Baytown plant, y'all state that "Steam is available to EDN from industrial park sources. An excess amount of steam is always

available to support startup and shutdown operations including those that are unplanned. That is, excess steam ensures that the SCR Unit remains ffully operational during SSM events. This unique circumstance limits the potential for emissions above permit limits, as well as the duration, during SSM events. "

I have bolden "unique". We appreciate your companys excellent efforts tin reducing NOx during SSM. Would like to get your thoughts on whether a typical new nitric acid plant could utilize your method of preheating the SCR or if only certain new plants could?

Thanks

Bill Neuffer Metals and Inorganic Chemicals Group Office of Air Quality Planning and Standards (D 243

- 02) US Environmental Protection Agency Research Triangle Park, NC 27711

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