Date: May 2012

Subject: Secondary Impact Analysis

Nitric Acid NSPS Review

EPA Contract No. EP

RTI Project No. 02103199.000.001

From: Melissa Icenhour

To: Nathan Topham

OAQPS/SPPD/M

U. S. Environmental Protection Agency

Research Triangle Park, NC 27711

As part of the NSPS Review for Nitric Acid Plants, it is estimated that 5 newly constructed nitric 

acid production units and 1 modified nitric acid production unit will become s

regulation in the next five years. See memo entitled

(Updated Memo for Final NSPS)

The purpose of this memo is to estimate the secondary impacts of 

reduction (SCR) control device on the modified production unit

modified source is able to meet the final emission rate of 0.50 lb 

100% nitric acid (0.50 lb NOX/ton

The secondary impacts from the installation of an SCR 

costs due to the increased electricity needed to operate the SCR. The increased electricity use 

leads to an increase in air pollutants

(CO2).

Secondary Impact Analysis—SCR

Nitric Acid NSPS Review

EPA Contract No. EP-D-11-084; Work Assignment No. 0-01 

RTI Project No. 02103199.000.001

OAQPS/SPPD/MICG (D243-02)

U. S. Environmental Protection Agency

Research Triangle Park, NC 27711

As part of the NSPS Review for Nitric Acid Plants, it is estimated that 5 newly constructed nitric 

acid production units and 1 modified nitric acid production unit will become subject to the 

regulation in the next five years. See memo entitled Impacts of Nitric Acid NSPS Review

(Updated Memo for Final NSPS) dated May 2012 in Docket No. EPA-HQ-OARThe purpose of this memo is to estimate the secondary impacts of installing a selective catalytic 

reduction (SCR) control device on the modified production unit. The SCR will ensure that the 

meet the final emission rate of 0.50 lb nitrogen oxides (NO

/ton acid) under Part 60, Subpart Ga.

The secondary impacts from the installation of an SCR include an increase in facility operating 

costs due to the increased electricity needed to operate the SCR. The increased electricity use 

ollutants such as NOX, sulfur dioxide (SO2), and carbon dioxide 

As part of the NSPS Review for Nitric Acid Plants, it is estimated that 5 newly constructed nitric 

ubject to the 

Impacts of Nitric Acid NSPS Review—NOX

-2010-0750.

installing a selective catalytic 

. The SCR will ensure that the 

nitrogen oxides (NOX) per ton 

include an increase in facility operating 

costs due to the increased electricity needed to operate the SCR. The increased electricity use 

), and carbon dioxide 
There is no known power equation specific to an SCR used to control NOX emissions from a 

nitric acid production train. However, according to EPA’s Air Pollution Control Cost Manual

(EPA Cost Manual), the amount of power consumed by an SCR used to control emissions from a 

utility boiler can be estimated using the following equation:

 = .  ∗   + .  +  Eq. 1 

where:

P = power (kW)

QB = boiler heat input (MMBtu/hr)

NOXin = concentration of NOX into the SCR (lb NOX/MMBtu)

ηNOX = destruction efficiency of the SCR

ΔPduct = pressure drop across ductwork (inches H2O)

ntotal = number of layers in the SCR

ΔPcatalyst = pressure drop across catalyst (inches H2O)

Equation 1 can be used to estimate the power requirement for an SCR installed on a nitric acid 

production train if we make some assumptions about the content of the gas entering the SCR.

According to EPA Method 19, the molar heat content of natural gas is 8,710 dry standard cubic 

feet (dscf) per million Btu (MMBtu).

According to the ICR from Agrium North Bend, the flow rate is 24,734 standard cubic feet per 

minute (scfm). Assuming minimal moisture content, this is 1,484,040 dscf per hour. Also 

according to the ICR, the SCR at the Agrium North Bend plant has 6 catalyst layers.

Table 1 contains actual data compiled by CRI Catalyst Company to show how much pressure 

drop is associated with the ductwork connecting the SCR to the emission stream. The average 

pressure drop is 7 inches H2O.

Using Equation 1, the power required to operate the SCR is 123.46 kilowatts (kW).

According to the EPA Cost Manual, the cost of electricity is directly related to the amount of power 

required to the run the SCR, as shown by Equation 2.

 =  ∗  ∗  Eq. 2

where:

C = cost of electricity ($)

P = power (kW)

EP = price of electricity ($/kWh)

OpHours = number of hours the plant operates the SCR during the year (hours)
According to the ICR, the plant operates 8,200 hours per year. The plant is operating in Ohio and 

according to this website (http://www.electricchoice.com/electricity-prices-by-state.php), the 

industrial cost of electricity was 6.06 cents per kilowatt-hour (kWh) in 2010.

Using Equation 2, the cost of electricity to operate the SCR is $61,352 per year.

According to this website (http://www.cleanerandgreener.org/resources/pollutioncalculator.html), 

electricity use results in the creation of other air pollutants including NOX, sulfur dioxide (SO2), 

carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O).

Using the known inputs for Equation 1 and Equation 2, shown in Table 2, the secondary impacts 

of this SCR are shown in Table 3.

As described in the preamble to this final rule, the secondary impacts are minimal.
Table 1. Pressure Drop Across SCR units at Nitric Acid Plants

Start Country

Capacity 

(mt/day) Process

Flue gas 

(Nm3/hr)

Temp

(C )

Pressure 

(bar)

NOX in 

(ppmv)

NOX out 

(ppmv)

NH3 out 

(ppmv)

PD 

(mbar)

PD 

(inch

H2O)

1995

South 

Africa 550 Krupp Uhde 70 205 1 1500 200 35

1998 Denmark 225 Krupp Uhde 30 210 3 1200 200 10 30 12

1999 USA 200

Grand 

Paroisse 27 190 6 2000 80 30 5 2

1999 USA 100 Weatherly 14,000 166 1 2100 100 10 20 8

1999 USA 200 Girdler 27.5 229 1 4800 400 30 20 8

1999 USA 180 21.5 450 - 515 6 3400 100 20

1999 Malaysia Cominco 31,500 477 6 1300 130 -

2000 Taiwan Stamicarbon 46,000 187 6,2 1200 100 35

2000 India Stamicarbon 8,100 200 1 4000 100 175 10 4

2000 Spain 370 Espindesa 50 220 3,5 4000 200 5

2001

Netherla

nds 2000

Grand 

Paroisse 260 265 10,4 250 32 5 10 4

2003

Netherla

nds 1700

Grand 

Paroisse 210,000 340 9 250 32 5 10 4

2001 UK 825 Krupp Uhde 107 225 6,5 1000 50 5 25 10

2001 UK 1100 Krupp Uhde 145,000 380 11,5 500 50 5 25 10

average

17 7

Information from CRI Catalyst Company

Nitric acid units with Shell DeNOX System

http://www-static.shell.com/static/cri_catalyst/downloads/business/cracker_fun_june2001.pdf
Table 2. Known Values

Element Source Value

Molar heat content of natural gas EPA Method 19; Table 19-2 8,710 dscf/MMBtu

Flow rate of gas entering the SCR ICR-Agrium North Bend 1,484,040 dscf/hr

Destruction Efficiency of SCR (ηNOX) Engineering Judgment 0.90

Pressure drop across catalyst (ΔPcatalyst) EPA Cost Manual 1.0 in H2O per layer

Number of catalyst layers (ntotal) ICR-Agrium North Bend 6

Pressure drop across the ductwork (ΔPduct) Table 1 7.0 in H2O

Uncontrolled NOX concentration Engineering Judgment 500 ppm

Operating hours (OpHours) ICR-Agrium North Bend 8,200 hours

Price of electricity (EP) Electricity Choice website 6.06 cents per kWh

NOX emissions from electricity use Cleaner and Greener website 3.3 lb per 1,000 kW

SO2 emissions from electricity use Cleaner and Greener website 13.2 lb per 1,000 kW

CO2 emissions from electricity use Cleaner and Greener website 1,911 lb per 1,000 kW

CH4 emissions from electricity use Cleaner and Greener website 0.02 lb per 1,000 kW

N2O emissions from electricity use Cleaner and Greener website 0.03 lb per 1,000 kW
Table 3. Calculated Values

Element Source Value

Boiler Heat Input (QB) (Flow rate of gas entering the SCR) 

/ (Molar heat content of natural gas)

170.4 MMBtu/hr

Power (P) Equation 1 123.46 kW

Total cost of electricity (C) Equation 2 $61,400

NOX emissions from operation of SCR Cleaner and Greener website 0.407 lb

SO2 emissions from operation of SCR Cleaner and Greener website 1.630 lb

CO2 emissions from operation of SCR Cleaner and Greener website 235.940 lb

CH4 emissions from operation of SCR Cleaner and Greener website 0.002 lb

N2O emissions from operation of SCR Cleaner and Greener website 0.004 lb