MEMORANDUM

Date: September 27, 2010

Subject: Site Visit – El Dorado Nitrogen, L.P

Baytown, Texas

Nitric Acid Manufacturing NSPS Review

EPA Contract No. EP-D-06-118; EPA Work Assignment No. 4-03

RTI Project No. 0210426.004.003

From: Melissa Icenhour

To: Bill Neuffer

EPA/SPPD/MMG (D243-02)

U. S. Environmental Protection Agency

Research Triangle Park, N.C. 27711

I. Purpose

The purpose of this visit was to observe the nitric acid manufacturing process at the 

El Dorado Nitrogen facility in Baytown, Texas, and to collect information on sources of nitrogen 

oxide (NOX) emissions and abatement controls in support of the review of new source 

performance standards (NSPS) for the nitric acid manufacturing industry.

II. Place and Date

El Dorado Nitrogen, L.P

8490 W. Bay Road

Baytown, Texas 77522-2469

May 12, 2010

III. Attendees

The Fertilizer Institute (TFI)

Chris Leason, TFI Counsel

Bill Herz, TFI President
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El Dorado Nitrogen, L.P

Jerry Davis, Plant Manager

Mike Barber, Process Manager

LSB Industries

Chuck Nestrud, outside counsel for LSB Industries

John Carver, Vice President of Safety and Environmental Compliance

Bayer Material Science

Gregg Stansfield, Fenceline Operations Manager

HSG Environmental Consultants

Ken Green

U. S. Environmental Protection Agency

Bill Neuffer

Tina Ndoh

Mausami Desai

Nathan Frank

RTI International

Melissa Icenhour

IV. Discussion

A. Background

The El Dorado Nitrogen, L.P. facility in Baytown, Texas, manufactures nitric acid. The 

site of the plant is owned by Bayer Corporation but El Dorado Nitrogen, a subsidiary of LSB 

Industries, serves as guest operator to produce feedstocks for use by Bayer. The nitric acid 

produced on-site is not used for fertilizer but is used for industrial chemicals. The facility 

contains a computerized, dual pressure, single train process that produces 65% nitric acid. 

According to Mr. Davis, a dual pressure process is usually chosen when the nitric acid 

concentration is greater than 65% and production is greater than 900 tons per day. The highest 

concentration of nitric acid from single pressure processes making nitric acid for producing 

fertilizer is typically 58%. 

The Bayer Material Science plant began operating about 1960 and is about a mile long. 

Bayer’s older nitric acid unit was torn down prior to 1999 when the current operation was built. 

The plot size of the plant is approximately 300 feet by 400 feet. The plot size limits expansion 

possibilities.

B. Introductions and Presentation

All attendees began with a brief introduction including their involvement in the 

regulatory process. Jerry Davis then gave a presentation that covered the nitric acid production 
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process; permit limits; the chemistry used to produce nitric acid; the use of selective catalytic 

reduction (SCR) for emission reductions; startup, shutdown, and malfunction (SSM) operations; 

and emissions that originate from other sources than the absorption column. Attachment 1 is a 

non-confidential version of the presentation given by El Dorado Nitrogen, L.P. The following 

paragraphs supplement the information presented in the attachment.

C. Process

The process at the Baytown, Texas plant is typical in the chemistry of nitric acid 

production but atypical in design. The first step in nitric acid production, oxidation of ammonia 

to nitrogen oxide, is typical. The ammonia supply to the process is about 0.29 tons of ammonia 

per ton of nitric acid.

The second step, oxidation of nitrogen oxide (NO) to nitrogen dioxide (NO2) is atypical 

in design. The amount of nitrogen dioxide produced during the second oxidation step is more

important at this plant than other plants where the nitric acid is used for fertilizer production. In 

order to meet the requirements of their client, the El Dorado Nitrogen plant must produce nitric 

acid at 65% concentration. To reach this concentration and maintain environmental compliance, 

the plant must increase the amount of nitrogen dioxide created during the second oxidation step. 

The only way to increase the yield of nitrogen dioxide is to increase the time wherein the 

oxidation can take place. While oxidation only takes a few seconds, the material process flow 

through pipes and equipment is rapid. The process design increases the amount of piping 

between the beginning of the second oxidation step and the absorption tower. For example, if 

the gas flow through the pipes were 300 feet per second, there must be 300 feet of pipe for every 

second of oxidation time needed during the second step. The increased amount of pipe area

serves as oxidation reactors. As a result, this nitric acid plant looks a bit different than typical 

fertilizer type nitric acid plants. 

Another difference between the typical nitric acid plant and the El Dorado Nitrogen plant 

is the availability of high pressure steam. At typical plants, shutdown of the nitric acid process 

also results in shutdown of the steam turbine, compressors, the expander, and any abatement 

technology. It takes time when starting the plant to create enough steam to operate the steam 

turbine/compressor train and increase the process pressure to allow absorption of the nitrogen 

dioxide. Until there is enough steam for absorption to take place, the nitrogen dioxide is emitted 

instead of reacted.

Bayer owns the site of the El Dorado Nitrogen plant and also has other types of chemical 

processes nearby. These other chemical processes offer an unlimited amount of steam that can 

be accessed by the El Dorado Nitrogen plant at any time, which allows the compressor train to 

run even if the nitric acid process is not running. Thus, the facility can remain in compliance 

with hourly NOX and ammonia concentrations at all times, even during periods of startup and 

shutdown. 

The third difference between the El Dorado Nitrogen plant and a typical nitric acid plant 

is the absorption tower. A typical absorption tower is about 150 feet tall and operates at a 

pressure of 150 pounds per square inch gauge (psig). The El Dorado Nitrogen absorption tower 
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is 210 feet tall, has 34 trays, and operates at a pressure of 170 psig. The design of the SCR 

deNOX system is based on an inlet concentration of NOX of 600 ppm. The unlimited steam that 

can be accessed on-site also allows the absorption tower and SCR to remain operating and thus 

reduce the amount of nitrogen dioxide that is emitted from the plant during typical startup and 

shutdown operations.

Process maintenance includes changing the ammonia oxidation catalyst about every 6 

months as it loses activity and becomes brittle, causing loss of precious metal catalyst. The plant 

generally undergoes an extensive maintenance shutdown every two years.

D. Emissions and Controls

Emissions from the absorption tower include nitrogen oxides (NOX) and nitrous oxide 

(N2O). The nitric acid production process is controlled by SCR at 650 oF, which controls NOX

emissions but does not control N2O emissions. The catalyst used in the SCR system typically 

has a longer life than a catalyst used in a nonselective catalytic reduction (NSCR) system. The 

amount of catalyst used in the SCR system depends on the ratio of NO to NO2. If the ratio is 

higher than 50%, the amount of catalyst should be increased.

The plant has the following permit limits:

• Ammonia (NH3) slip of 20 ppmv (hourly and annual average),

• NOX emissions of 23 pound per hour, and 

• NOX emissions of 71 tons per year.

The plant uses a Grande Paroisse zeolite catalyst, which may cause nitrous oxide (N2O) 

formation. The plant has no permit limits for N2O. 

The capital cost of the unit in 1999 was about $80 million. The SCR catalyst typically 

costs $500,000 and has a life expectancy of greater than 10 years.

The plant uses extractive Fourier Transform Infrared (FTIR) technology to monitor NO, 

NO2, NH3, and N2O emissions.

The plant has 5 nitric acid storage tanks operating at slight negative pressure. The vapor 

emissions from the tanks are controlled by a packed bed scrubber with hydrogen peroxide

solution. The liquid effluent from the scrubber is recycled. Some NOX and acid mist are 

emitted.

Typically the plant emits pollutants in the following concentrations:

• N2O—1200 ppm,

• NO2—10 ppm,

• NO—10 ppm, and

• NH3—1 ppm.
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E. Conclusions

This plant is relatively new, efficiently designed, and has low NOX emissions. These 

factors made this plant an ideal candidate for a site visit. Industry representatives who attended 

this site visit and presentation stated that the plant is not a typical nitric acid plant and the low 

emissions achieved by this plant are not achievable by all nitric acid plants.
Attachment 1

Non-Confidential Presentation

Provided by El Dorado Nitrogen, L.P.