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Icenhour, Melissa K.

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

Sent: Friday, October 08, 2010 3:17 PM

To: Neuffer.Bill@epamail.epa.gov

Cc: Icenhour, Melissa K.; Laney, Michael N.

Subject: RE: NSPS Nitric Acid - Monitoring Question

Bill,

Methods for reporting an official daily production rate may vary from plant to plant. In our 

case we have our "official daily production" as an accounting function. If we did not do 

this then we would end up with two figures, because no two meters or measuring systems will 

be in perfect agreement. For sure we only get credit (financially) for what we sell. If we 

used a meter on the acid from out plant, then at the end of the day/ month/ year there would 

be two numbers.

Some plants may have some type of production indication system/meter on their plant, but to 

measure production is very difficult because production is reported as 100% nitric acid when 

in reality there will be 30 to 50% water in the stream. So, to "measure" instantaneous " 

production, it is required to have instrumentation that can measure total wet flow, some 

analyzer or instrumentation that can determine what percent of the flowing stream is nitric 

acid and then multiply the two (wet flow x % acid). There are a lot of inaccuracies in both 

the wet flow meter and any "analyzer"; when you multiply them, it multiplies the inaccuracy. 

Thus, you see why we and I think almost all plants, strive to get an accounting production 

number (acid sold + inventory adjustment) ; that number, whether right or wrong, is the 

number that goes on the financial books and provides the financial backing for the operation.

Another issue comes up on any attempt to measure acid flow directly from the plant during 

startup, shutdowns and malfunctions. During these periods, the acid can be very low 

concentration where any analyzer used would be out of range and give very incorrect results. 

Any plant that may have some type of metering system for production indication can just 

ignore these times as the flow indication is only to assist plant operations and has no 

"official" status.

An additional, but similar issue comes about when the plant is in a maintenance shutdown and 

is being flushed with water to clear/ clean the equipment for personnel entry. This flush 

water would go through the meter and register as a flow while the plant was not in operation. 

Again, when it is not official, it can be ignored without issue.

During startup, the product is below the acid percent specification. During this time, the 

acid may flow through a plant meter that would register as "production", but go to a startup 

tank. Later, after the plant is lined out making on spec acid, this "startup acid" would be 

worked off slowly by recycling it to the plant absorber tower. As it comes out of the plant 

a second time, any flow indication system from the plant would pick it up double measuring 

the same acid. Again, this is not a problem for any plant that has an operations flow/ 

production indication meter, because it is not official and can be ignored as a true 

indication of plant production during this time.

I hope this helps you understand why I think our plant is typical and uses the accounting 

daily production as the official reported number for the plant production. This one number 

is used for all stakeholders, including regulatory.

A last thought is what if the regulations attempt to regulate NOx per measured production ton 

on an hourly basis, what is the definition of when the nitric acid is produced? In the 

absorber column, there are large levels of acid on each tray where the NOx is actually 

reacting with the water. After the plant us "shutdown", which we usually define as when the 

ammonia flow to the AOR is stopped, then the compressor is shutdown and the absorber begins 
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to drain. There is a large amount of nitric that comes out of the "plant" at that time which 

may take a few hours. In the regulations, which NOx emission will be associated with that 

nitric acid when calculating a NOx emission per measured ton of nitric acid? Could be a 

tough question if left to each plant to define. During startup, if the absorber starts with 

only water on the trays, acid will be made on the trays, but not discharged to storage until 

the strength is in specification; acid is being "made" and NOx is being emitted from the 

plant, but no measured product is going to storage- the regulations would have to address 

this if a NOx emission per measured ton on an hourly basis is the permit limit.

Many plant approximate production based on the amount of ammonia flow to the AOR. If someway 

the regs used this approach, it may be easier to calculate and more meaningful in the long 

run on a short time (hourly) basis.

I hope your final rules will clearly address nitric plant, startups, shutdowns and 

upset/malfunctions. This will be interesting to see what your group ends up with. Good luck.

Hope all this helps,

Jerry

-----Original Message-----

From: Neuffer.Bill@epamail.epa.gov [mailto:Neuffer.Bill@epamail.epa.gov]

Sent: Wednesday, October 06, 2010 9:39 AM

To: Jerry Davis

Cc: Icenhour, Melissa K.; Laney, Michael N.

Subject: RE: NSPS Nitric Acid - Monitoring Question

The air flow monitoring would be done at the stack. With this measurement and the NOx CEM 

one would know lb/hr of NOx emitted.

Another question - the present NSPS requires daily production rate.

How is this usually determined? Is measuring of hourly production rate usually done? If so, 

by what methods? Is hourly production difficult to measure?

Thanks as always.

Bill Neuffer

Metals and Minerals 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

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 |RE: NSPS Nitric Acid - Monitoring Question 

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Bill,

Good to hear from you. My thoughts on the points you raise follow:

Opacity: I do not feel opacity is of any value when we are achieving low NOx levels. The 

analyzer monitoring NOx is all that makes sense. If industry is meeting the PPM limits, 

there will be no opacity.

Air monitoring: I am not sure what the consideration/ justification/ environmental benefit 

for monitoring air flow (I assume to the reactor) would be. During startup an shutdown, we 
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have air flow when we are not burning ammonia. Any correlation to emissions from air flow 

may not be correct. It should not be a problem for any company as all companies monitor this 

flow for operational reasons. I would need more information on your justification/ thinking 

to give you any thoughts that could help.

Regards,

Jerry

-----Original Message-----

From: Neuffer.Bill@epamail.epa.gov [mailto:Neuffer.Bill@epamail.epa.gov]

Sent: Wednesday, September 15, 2010 8:14 AM

To: Jerry Davis

Cc: Icenhour, Melissa K.; Neulicht, Roy

Subject: NSPS Nitric Acid - Monitoring Question

Jerry,

 Hope you are doing well.

 We are considering adding to this NSPS a monitoring requirement to continually 

monitor air flow rate. We are also thinking of deleting the requirement for opacity 

monitors.

 Any thoughts?

 Thanks

Bill Neuffer

Metals and Minerals 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