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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 careful 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 malfunction.

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 minimum 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 temperature 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 direct 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 valve 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.
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Hope 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 during 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

Phone - 919-541-5435

Fax - 919 - 541-3207

E-mail - neuffer.bill@epa.gov

Office Location: 109 TW Alexander Drive RTP, NC (D 231C)

Overnight mail address:

US EPA

Mail Code D243-02

109 TW Alexander Drive

RTP, NC 27709