Article VI 

Technical Support 
Lorain Plant

ReasonablyAvailable Control

Technology- NOxEmissions

Prepared by: Environmental Quality Management, Inc.

1800 Carillon Boulevard

Cincinnati, OR 45240-2788

Prepared for: Republic Engineered Products - Lorain Plant

1807 East 28th Street

Lorain, OR 44055-1883

Submitted to the Ohio Environmental Protection

Agency, Northeast District Office

December 22, 2008

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EXECUTIVE SUMMARY

Ohio Administrative Code (OAC) Chapter 3745-110 requires affected sources to employ

reasonably available control technology (RACT) for nitrogen oxide (NOx) emissions. For an

existing source other than an industrial boiler, stationary combustion turbine, or stationary internal

combustion engine the owner or operator is required by OAC rule 3745-110-03(1) to complete and

submit an engineering analysis ofRACT for NOx emissions. Sources owned by Republic

Engineered Products, Inc. (Republic) Lorain Plant that require a RACT study are the 10" Walking

Beam Furnace (Emissions Unit P07l) and the Bloom Reheat Furuace (Emissions Unit P08l).

Emission Units P07l and P08l are both recuperative-style reheat furnaces that currently

employ 10w-NOx burner technology. Each furnace is tested on an annual basis to demonstrate

compliance with the allowable NOx emission limit found in Republic's effective Title V permit;

P07l - 0.15lb/MMBtu, P08l - 0.132lb/MMBtu. The installation ofthe 10w-NOx burners and

corresponding emission limits were mandated by consent decree.

The NOx RACT analysis for the 10" Walking Beam Furuace and the Bloom Reheat Furnace

examines three combustion control techniques: 10w-NOx burners (LNB), low-excess air (LEA) and

oxy-fuel burners, and two post-combustion, add-on control technologies: selective catalytic

reduction (SCR) and selective non-catalytic reduction (SNCR).

The combustion modification techniques, LEA and flue gas recirculation, have operational

drawbacks that could adversely affect furnace temperature profiles and cause uneven steel heating.

For this reason these modification are not "technically feasible" and are therefore not considered

RACT for either source. In addition, the installation ofOxy-fuel burners would result in minimal

NOx reduction at an excessive cost, thus it is also not considered RACT for these sources.

The add-on control technologies evaluated (SCR and SNCR) also do not represent RACT

for these sources. Retrofit SCRs systems are not cost-effective for either furnace and SNCR is not

technically feasible because the furnace exhaust gas temperatures are significantly less than the

effective operating range for this technology.

In conclusion, NOx RACT for the for the 10" Walking Beam Furnace and the Bloom Reheat

Furnace is determined to be the continued operation ofthe 10w-NOx burners at the current NOx

emission limits from Republic's Title V permit ofO.15Ib/MMBtu for P07l and 0.1321b1MMBtu

for P081.

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TABLE CONTENTS

Section Page

Executive Summary 11

Table ofContents iii

1 Introduction 1

1.1 Background 1

1.2 Source Description 1

1.3 Affected Emission Units 3

2 NOx RACT for 10" Walking Beam Furnace and Bloom Reheat Furnace 6

2.1 Emission Unit Description 6

2.1.1 10" Walking Beam Furnace (P071) 6

2.1.2 Bloom Reheat Furnace (P081) 7

2.2 Case-by-Case NOx RACT Determination 8

2.3 Combustion Control Techniques 8

2.3.1 Low NOx Burners 9

2.3.2 Low Excess Air 9

2.3.3 Oxy-Fuel Burners 11

2.4 Post-Combustion Add-On Control Technologies 12 ~:

2.4.1 Selective Catalytic Reduction 12

2.4.2 Selective Non-Catalytic Reduction 14

2.5 NOx RACT Conclusion 16

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SECTION 1

INTRODUCTION

1.1 BACKGROUND

Ohio Administrative Code (OAC) rule 3745-110-03(1) requires an owner or operator of

affected existing sources other than industrial boilers, stationary combustion turbines, or

stationary internal combustion engines to complete and submit an engineering analysis of

reasonably available control technology (RACT) for NOx emissions. This RACT study must be

submitted to Ohio EPA's Northeast District Office on or before December 22, 2008.

Sources owned by the Republic Engineered Products, Inc. (Republic) Lorain Plant that

require a NOx RACT study are the 10" Walking Beam Furnace (P071) and the Bloom Reheat

Furnace (P081). This report satisfies that requirement.

1.2 SOURCE DESCRIPTION

Republic Engineered Products, Inc. (Republic) operates a hot rolled bar plant in Lorain,

Ohio. The plant is located at 1807 East 28th Street and operates under the Title V permit for

Facility ID: 02-47-08-0299 effective June 20, 2003 (a permit renewal application has been

submitted to Ohio EPA). The standard industrial classification code number that is applicable to

this facility is 3312 - Blast Furnaces and Steel Mills. Figure I shows the location ofthe 10"

Walking Beam Furnace and the Bloom Reheat Furnace at Republic's Lorain Plant.

The operator's representative within the company who is the contact person for this

facility regarding the NO, RACT engineering study and affected sources is:

Mr. Jay E. Lawniczak

Enviromnental Affairs Manager

1807 East 28th Street

Lorain, Ohio 44055-1883

Telephone Number: (440) 277-3088

The company official responsible for approval ofthis engineering study is:

Mr. Curt Anderson, Director ofOperations

Republic Engineered Products, Lorain Division

1807 East 28th Street

Lorain, Ohio 44055-1883

Telephone Number: (440) 277-3400

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Figure 1. Locations of 10" Walking Beam Furnace and Bloom Reheat Furnace at Republic's Lorain Plant (Map from Google)

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The Lorain Plant is a major stationary source for NOx emissions. Republic operates two

NOx emission units that are applicable to this RACT study:

• Emissions Unit: P071 10" Walking Beam Furnace

• Emissions Unit: P081 Bloom Reheat Furnace

1.3 AFFECTED EMISSION UNITS

The 10" Walking Beam Furnace and the Bloom Reheat Furnace are each subject to the

applicable NOx RAeT requirements under OAC rule 3745-110-03(1). Section 2 below describes

the respective NOx RACT determinations for these two reheat furnaces.

The 10" Walking Beam Furnace (P071) is a recuperative furnace that reheats up to 2,064

tons per day ofsteel billets from ambient temperature to 2,100°F. The furnace and fuel rates are

based on Type 1008 steel. There is essentially no thermodynamic difference in heating carbon

steels, however, metallurgical requirements may govern these rates for higher alloy and/or heat

sensitive steels. The furnace is a top and bottom fired walking beam type reheat furnace that is

refractory lined with a water cooled pipe billet support and transport system, and a recuperative

heat recovery combustion system (the hot exhaust gases are used to heat the incoming

combustion air in an indirect air-to-air heat exchanger or recuperator). The furnace is fired by 75

low NOx burners located in five heating zones (three top zones and two bottom zones). Table I

presents the design and operating parameters pertinent to this NOx RACT study required by

OAC rule 3745-110-03(1). P071 normally operates 24 hrs/day, 6 days/week (24 hours downtime

per week).

The Bloom Reheat Furnace (P081) is a recuperative furnace that reheats up to 4,080 tons

per day ofsteel blooms from ambient temperature up to 2,IOO°F. The furnace is a top and

bottom fired walking beam type reheat furnace that is refractory lined with a water cooled pipe

billet support and transport system, and a recuperative heat recovery combustion system. The

furnace is fired by 55 low NOx burners in eight heating zones (four top zones, three bottom

zones, and one screen zone). Table 2 presents the design and operating parameters pertinent to

this NOx RACT study required by OAC rule 3745-110-03(1). P081 normally operates 24

hrs/day, 6 days/week (24 hours downtime per week).

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TABLE 1. 10" WALKING BEAM FURNACE NOx EMISSIONS AND RELATED

DESIGN AND OPERATING INFORMATION

pon 10" Walking Beam

Furnace 2007 2006 200S Referenee

Maximum Heat Input, 206 206 206 Design MMBtu/hr

Maximum fuel usage, MMCF/hr 0.200 0.200 0.200 Based on 1,030 Btu/cf

Number of Bumers 75 75 75 Design

NO" Concentration, ppm 38.2 38.72 48.74 Stack Test

NO, Emissions, lb/MMBtu 0.095 0.097 0.093 Stack Test

Oxygen Concentration in Stack 12.09 12.13 9.45 Stack Test Gas, %

Production, tons 364,954 401,258 343,800 Fee Report

Annual fuel use, MMBtu 660,055 680,082 558,601 Fee Report

Annual fuel use, MMCF 640.830 660.274 542.331 Fee Report

NO, Emission Factor, lb/MMCF 100.94 100.94 100.94 Fee Report

NOx Emissions, TPY 32.34 33.32 27.37 Fee Report

Exhaust Flow Rate, acfm 102,935 102,935 102,935 12114/2005 Stack Test

Temperature, OF 744 744 744 12/]4/2005 Stack Test

Title V Permit Limit, lb 0.15 0.15 0.15 Title V Permit NOjMMBtu

Average Daily Production, 1,106 1,216 1,042 Based on 330 days of

tons/day operation

Average Daily NO" Emissions, 196 202 166 Based on 330 days/yr and

lb/day emissions from Fee Statement

Maximum Daily Production, 2,064 2,064 2,064 Title V Permit Application tons/day

Maximum Daily NO, Based on Permit Limit, max

Emissions, 1b/day 742 742 742 heat input and 24 hr/day

operation

Annual NOx Emissions, TPY 32.34 33.32 27.37 Fee Report

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TABLE 2. BLOOM REHEAT FURNACE NO. EMISSIONS AND RELATED

DESIGN AND OPERATING INFORMATION

P081 Bloom Reheat Furnace 2007 2006 2005 Refereuce

Maximum Heat Input, 421.6 421.6 421.6 Design . MMBtu/hr

Maximum Heat. Input, 0.409 0.409 0.409 Based on 1,030 Btu/cf MMCF/hr

Number of Burners 55 55 55 Design

NOx Concentration, ppm 32.71 93.28 67.93 Stack Test

NO, Emissions, Ib/MMBtu 0.044' 0.127 0.111 Stack Test

Production, tons 622,026 642,244 497,262 Fee Report

Oxygen Concentration in Stack 4.65 4.87 7.56 Stack Test Gas, %

Annual fuel use, MMBtu 1,392,560 1,322,211 1,307,170 Fee Report

Annual fuel use, MMCF 1,352 1,284 1,269 Fee Report

NO, Emission Factor, Ib/MMCF 84 84 84 Fee Report

NOx Emissions, TPY 56.784 54.211 53.590 Fee Report

Exhaust Flow Rate, aefm 216,987 216,987 216,987 Ratio P0811P071 heat inputs

and P071 exhaust gas flow

Temperature, OF 744 744 744 Based on P071 Exit gas

Temperature

Title V Permit Limit, Ih 0.132 0.132 0.132 Title V Permit NO,lMMBtu

Average Daily Production, 1,885 1,946 1,507 Based on 330 days of

tons/day operation

Average Daily NOx Emissions, 344 329 325 Based on 330 days of

Ib/day operation per year

Maximum Daily Production, 4,080 4,080 4,080 Design tons/day

Maximum Daily NO, Based on Petmit Limit, max

1,336 1,336 1,336 heat input and 24 hr/day Emissions, Ib/day oocration

Annual NO, Emissions, TPY 56.78 54.21 53.59 Fee Report

a NO, results from stack test performed on Apnl 8, 2008 as follow-up to stack test performed on

November 13,2007 that showed an average NOx emission rate ofO.l411b per MMBtu (98.34

ppm).

5
SECTION 2

NO, RACT FOR THE 10" WALKlNG BEAM FURNACE

AND THE BLOOM REHEAT FURNACE

2.1 EMISSION UNIT DESCRIPTIONS

The 10" Walking Beam Furnace (P071) and the Bloom Reheat Furnace (P081) are

recuperative-style steel reheat furnaces. These furnaces will be described separately but the

case-by-case RACT determinations will be performed together to avoid repetition throughout the

RACT analysis.

2.1.1 10" Walking Beam Furnace (P071)

The 10" Walking Beam Furnace is a recuperative furnace that reheats up to 2,064 tons

per day ofsteel billets from ambient temperature to 2,100°F. The combustion system is designed

for the use of natural gas only. The furnace was installed in 1995 as part of a consent decree.

See U.S. v. USSIKOBE Steel Co., Civ. Action No. 1:92CVI928 (N.D. Ohio 1992). The consent

decree mandated the installation oflow-NOx burners as control technology and established the

NOx emission limit at 0.15 Ibs NOx per million BTU. Emissions Unit P071 is a five-combustion

zone walking-beam furnace that burns natural gas as the primary fuel. The furnace has a

combined heat input capacity from a total of75 burners of 206 MMBtu/hr. The primary

combustion zones are the soak, heat, and preheat zones and are further divided as follows:

• twenty-four 1.6 MMBtu/hr burners in the top soak zone (38 MMBtu/hr),

• sixteen 1.75 MMBtu/hr burners in the top heat zone (28 MMBtu/hr),

• sixteen 2.2 MMBtu/hr burners in the top preheat zone (35 MMBtu/hr),

• nine 6.2 MMBtu/hr burners in the bottom soak zone (55 MMBtu/hr), and

• ten 5 MMBtu/hr in the bottom preheat zone (50 MMBtu/hr).

The 10" Walking Beam Furnace is a recuperative furnace, meaning that the combustion

air is preheated with furnace exhaust gases in a recuperator. The burners are a low-NOx burner

,design and were manufactured by the North American Manufacturing Company. These

recuperative burners have a standard low-NOx design utilizing flame configuration and baffling

to reduce NOx generation without restricting heat transfer or fuel economy. The burners have a

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NO, rating ofno greater than 0.15 Ib NOx per MMBtu heat input and comply with the Title V

pennit requirement of 0.15 lb NO, per MMBtu heat input.

The 10" Walking Beam Furnace NOx emission compliance tests are perfonned annually

as required by Republic's Title V pennit. The average emission rates measured using EPA

Method 7E from 2005 through 2007 were:

• 48.74 ppm and 0.0931b/MMBtu from the December 14, 2005 test,

• 38.72 ppm and 0.097 Ib/MMBtu from the September 13, 2006 test, and

• 38.2 ppm and 0.095 Ib/MMBtu from the November 13, 2007 test.

2.1.2 Bloom Reheat Furnace (POSl)

The Bloom Reheat Furnace (P081) is a recuperative furnace that reheats up to 4,080

tons per day ofsteel blooms from ambient temperature to 2,100°F. The combustion system is

designed for the use of natural gas only. This furnace was also installed in 1995 as part the

USS/KOBE consent decree. See u.s. v. USSIKOBE Steel Co., Civ. Action No. 1:92CVl928

(N.D. Ohio 1992). The consent decree mandated the installation ofiow-NOx burners as control

technology and established the NOx emission limit of 0.132 lbs NOx per million BTU. The

system was subsequently upgraded in 1999 through the modification ofthe fuelsupply from

mixed gas to natural gas allowing a reduction of excess air to the furnace which improved the

furnace's efficiency. Emissions Unit P08l is an eight-combustion zone, walking-beam furnace

which is restricted to burning natural gas. The furnace has a combined heat input capacity from

a total of 55 burners of421.6 MMBtu/hr. The primary combustion zones are the soak, heat, and

preheat zones and are further divided as follows:

• nine 1.0 MMBtu/hr burners in the east top soak zone (9MMBtu/hr),

• nine 1.0 MMBtu/hr burners in the west top soak zone (9 MMBtulhr),

• six 11.3 MMBtu/hr burners in the top heat zone (67.8 MMBtu/hr),

• six 11.3 MMBtulhr burners in the top preheat zone (67.8 MMBtulhr),

• five 8.0 MMBtulhr burners in the bottom soak zone (40 MMBtu/hr)

• eight 13.75 MMBtu/hr burners in the bottom heat zone (110 MMBtu/hr),

• six 16.66 MMBtulhr burners in the bottom heat zone (100 MMBtulhr), and

• six 3.0 MMBtulhr in the screen zone (18 MMBtulhr).

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The Bloom Reheat Furnace is a recuperative furnace, meaning that the combustion air is

preheated with furnace exbaust gases in a recuperator. The burners are a 10w-NOx burner design

and were manufactured by the Bloom Engineering Company. These recuperative burners have a

10w-NOx design that injects fuel and combustion air in such a manner tbat minimizes their

contact in the burner port. The burners have an overall NOx rating of no greater than O.l321b

NOx per MMBtu heat input and comply with the Title V pennit requirement of 0.132 Ib NOx per

MMBtu heat input.

The Bloom Reheat Furnace compliance tests are perfonned annually as required by

Republic's Title V pennit. The average emission rates measured using EPA Method 7E from

2005 through 2007 were:

• 67.93 ppm and 0.111 Ib/MMBtu from the December 9,2005 test,

• 93.28 ppm and 0.127Ib/MMBtu from the November 15,2006 test, and

• 32.71 ppm and 0.044 Ib/MMBtu from the April 8, 2008 test. [Note: This was a retest of

tests conducted on November 13,2007 with results of98.3 ppm NOx or O.l41Ib/MMBtu]

2.2 CASE-BY-CASE NOx RACT DETERMINATION

As described in the Alternative Control Techniques Document - NO, Emissions from Iron

and Steel Mills (EPA OAQPS, EPA-453/R-94-065, September 1994), combustion control options

for steel reheat furnaces include low excess air (LEA), 10w-NOx burners (LNB), and flue gas

recirculation (FGR). Another option not mentioned in the Control Techniques Document that we

assessed is the use of oxy-fuel burners. Available post-combustion add-on NOx control

technologies potentially applicable to steel reheat furnaces include selective catalytic reduction

(SCR) and selective non-catalytic reduction (SNCR).

There are several other NOx control techniques that are listed in OAC rule 3745-110-

03(I)(I)(h) that are not applicable to steel reheat furnaces. Table 3 lists these NOx control

techniques and comments on their applicability to steel reheat furnaces.

2.3 COMBUSTION CONTROL TECHNIQUES

This case-by-case NOx RACT analysis for the Emission Units P071 and P081 examined

three combustion control techniques: LNB, LEA, and oxy-fuel burners. Flue gas recirculation

(FGR) was not considered because both furnaces are recuperative furnaces and FGR is not

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applicable for these types offurnaces. Other combustion modification and control techniques,

such as over-fire air (OFA), burners-out-of-service (BOOS), and staged combustion, were not

examined in detail. These combustion modification techniques are generally applicable to

boilers and not to steel reheat furnaces.

2.3.1 Low NO, Burners

Low-NO, burners are specially designed burners that are engineered to reduce thermal

NOx by controlling flame temperature, oxygen concentration, or other combustion parameters.

Both Emissions Units P071 and P081 currently employ low NOx burners which were installed as

part of a consent decree. See U.S. v. USSIKOBE Steel Co., Civ. Action No. I:92CVI928 (N.D.

Ohio 1992). Based on the most recent stack test for both ofthe furnaces, the 10" Walking Beam

Furnace has an average NOx emission rate ofO.0951b NOx/MMBtu (38.2 ppm) and the Bloom

Reheat Furnace has an average NO, emission rate ofO.0441b NO,/MMBtu (32.7 ppm).

Republic's current emissions limits from its Title V permit are 0.151b NOx/MMBtu for P071 and

~JEJ1:> NOx/MMBtu for P081. Republic is required to demonstrate compliance with each

emission limit using EPA Method 7E procedures on an annual basis in accordance with the Title

V Permit requirements. The continued operation ofthe existing Low-NOx burners is considered

RACT for both sources.

2.3.2 Low Excess Air

Low excess air is a combustion modification technique in which NOx formation is

inhibited by reducing the amount of excess air used for fuel combustion to less than normal

ratios. This technique lowers the flame-zone oxygen concentration reducing thermal and fuel

NOx formation. Typical excess air ratios used for natural gas combustion in boilers and hightemperature process furnaces can range from 10 to 20 percent.

The potential ofLEA as a reasonable NOx control technique is limited by the

technology's potential to increase smoke (visible emissions) and carbon monoxide (CO)

emissions. Ifinsufficient combustion air is supplied to furnace burners, flame instability and

lower combustion efficiency may result causing increased smoke and CO emissions. In addition,

this could lead to uneven furnace temperature profiles and heat distribution. Inconsistent furnace

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temperatures would adversely affect billet reheating and the quality ofRepublic's rolled steel

products.

Low excess air is not considered RACT for either the 10" Walking Beam Furnace or the

Bloom Reheat Furnace. The 10" Walking Beam Furnace normally operates at about 20-40

percent excess air and the Bloom Reheat Furnace operates at about 10-30 percent excess air at

the burner during operation. Republic Lorain has developed furnace operating experience at

these current excess air ratios such that the billets or blooms are reheated properly and product

quality specifications are consistently met. The potential drawbacks to lowering the excess air

rate in the furnace (e.g., lower efficiency, uneven billet reheating, increased smoke and CO

emissions) do not justifY further consideration ofLEA as RACT.

2.3.3 Oxy-Fuel Burners

The use of oxy-fuel burners is a combustion modification technique in which NO,

formation is reduced by using oxygen gas to replace all or part ofthe combustion air through

burners designed to burn oxygen gas for fuel combustion. This reducesthe amount of nitrogen

in the combustion air stream. A drawback to this technology is that small deviations from

operating parameters can result in significant NOx emissions. See L. Arvidsson et. aI., Oxy-Fuel

- Demanding but Highly Rewarding. Nordic Steel and Mining Review 20-21 (Sweden, 2003).

Generally, oxy-fuel burners are added to reheat furnaces to increase production rather

than to T\"duce NO, emissions. Application of oxy-fuel combustion to the 10" Walking Beam

Furnace and the Bloom Reheat Furnace would require burner replacement and a source of

oxygen. Although there is an oxygen plant onsite for the Basic Oxygen Process (BOP),

cryogenic piping would need to be installed several hundred feet to carry the oxygen from the

BOP air separation plant to PO?I and P081. This assumes that the plant can produce sufficient

oxygen to supply both the BOP and the reheat furnaces. Ifnot, a new oxygen plant would need

to be installed and this cost could not be economically justified to control NO, emissions from

PO?I and P08l. In addition, the replacement ofthe existing low NO, burners with oxyfuel

burners would be necessary.

Based on available information, the use of oxy-fuel combustion would not significantly

decrease NO, emissions. One report suggests that oxy-fuel combustion would result in little or no

NOx reductions beyond what the existing 10w-NOx burners currently provide. See P. Fredriksson et.

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a!., Application ofOxyfuel Combustion in Reheating at Ovako Hofors Works, Sweden - Background,

Solutions and Results, Steel Rolling (Paris 2006) (stating that conventional oxy-fuel combustion

would reduce the NO, emissions to less than 0.10 Ib/MMBtu). The most recent stack test for the 10"

Walking Beam Furnace showed NOx emissions ofO.0951b NOjMMBtu and the NOx stack test for

the Bloom Reheat Furnace showed emissions ofO.0441b NOjMMBtu (NOTE: other stack tests for

P081.have shown NOx emissions closer to the permitted limit of 0.132 Ib NOx/MMBtu) which are

comparable to the expected emissions for oxy-fuel combustion. The application of oxy-fuel burners

is not RACT for either the 10" Walking Beam Furnace or the Bloom Reheat Furnace. The cost of

purchasing and installing oxy-fuel burners and supplying oxygen to the reheat furnaces cannot be

justified for little to no NO, reduction beyond what the low NO, burners currently accomplish.

These factors do not justify further consideration of oxy-fuel burners as RACT.

2.4 POST-COMBUSTION ADD-ON CONTROL TECHNOLOGIES

This case-by-case NOxRACT analysis for the 10" Walking Beam and the Bloom Reheat

Furnaces examines two post-combustion add-on control technologies: selective catalytic

reduction and selective non-catalytic reduction. The design description and operational

parameters of SCR and SNCR systems evaluated for applicability to the Billet Reheat Furnace

were taken from The EPA Air Pollution Control Cost Manual (EPA OAQPS, EPA-452/B-02-

001, January 2002).

2.4.1 Selective Catalytic Reduction

Selective catalytic reduction is a post-combustion add-on NO, control teclmology based

on the chemical reduction ofthe NO, molecule to Nz and H20. In an SCR system, ammonia

(NH3) is diluted with compressed air or steam and injected into the flue gas stream downstream

ofthe combustion unit and upstream of a catalyst reactor bed. The injected NH) reacts with the

NO, in the gas stream on the surface ofthe catalyst to form molecular nitrogen and water.

Typical SCR-system catalysts are based on a noble metal such as platinum, or oxides ofmetals

such as zirconium, vanadium, and titanium. The optimal reaction temperature range for the

majority ofSCR catalysts is 480 to 800°F. Less frequently used catalysts composed ofzeolites

or alumina silicates can have an effective reaction in the temperature range of 675 to 1,OOO°F.

II
Properly operated and efficient SCR systems require a very stable flue gas stream with

respect to flow rate, temperature, and NOx concentrations. Both the 10" Walking Beam and the

Bloom Reheat Furnaces operate continuously and thus offer a relatively consistent flue gas

stream. The exit gas temperatures ofboth furnaces (about 700 to 800°F) are also in the range of

applicability for SCR Controls.

The cost of an SCR system, however, is generally higher than the cost of other NOx

control systems. A budgetary cost estimate ofthe minimum capital and annual cost ofthe

system shows that an SCR installed on either the 10" Walking Beam Furnace or the Bloom

Reheat Furnace is not cost effective for removal ofNOx from these sources. The EPA Air

Pollution Control Cost Manual (EPA OAQPS, EPA-452/B-02-001, January 2002) estimates that

the installed capital cost of an SCR system to be $4,000 to $6,000 per MMBtu/hr for small oil

and gas-fired units to over $10,000 per MMBtu/hr for large coal-fired units in 1997 dollars.

Installing an SCR system on either Emissions Unit P071 or P08l would be a retrofit installation

so the installed cost for an SCR on these furnaces would be at least $10,000 per MMBtu/hr in

1997 dollars. In other words, the cost for installing an SCR on the 10" Walking Beam Furnace

would be roughly $2,060,000 and $4,216,000 for the Bloom Reheat Furnace. At least 20 percent

ofthe system's cost would be the catalyst that would need to be replaced approximately every 3

years. To estimate the annual capital recovery factor, in dollars, for an SCR system, a three year

catalyst life will be assumed and a 10 year life for the other installed equipment. These costs as

well as the cost effectiveness ofNOx removal are summarized as follows:

Cost Item

Total Capital Cost

Equipment Cost (80%)

Catalyst Cost (20%)

pon, $:

2,060,000

1,648,000

412,000

POSt, $:

4,216,000

3,373,000

843,000

Annual Cost Recovery is based on a 10 year life for equipment other than the catalyst, a 3

year life for the catalyst and 10 percent interest. The cost recovery factor for the equipment is

16.27 percent for the equipment and 40.2 percent for the catalyst. An 80 percent NOx removal

efficiency is assumed to calculate cost effectiveness. The annual costs do not include process

• All values reported in 1997 dollars.

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operating costs, ammonia or other chemicals, maintenance, or other recurring costs that are

normally included in a more rigorous cost estimate.

Estimated NOx Removed. 25,9 tons

Cost Item

Annual Cost Recovery

Equipment (16.7%)

Catalyst (40.2%)

Total Annual Cost

Cost Effectiveness

275,200

165,600

$440,800

$17,000 Iton NOx

563,300

338,900

$902,200

(45:4 tons

$19,800 Iton NOx

A more rigorous cost estimate in 2008 dollars would be considerably higher on a dollar

per ton ofNOx removed basis. The simplified and conservative cost estimate above shows that

SCR control ofNOx on either the 10" Walking Beam Furnace or the Bloom Reheat Furnace is

not cost effective and, therefore, not RACT.

2.4.2 Selective Non-Catalytic Reduction

Selective non-catalytic reduction is a post-combustion add-on NOx control technology

based on the chemical reduction ofthe NO, molecule to N2 and H20. In an SNCR system, a

nitrogen-reducing agent; e.g., gaseous ammonia (NH3) or liquid urea, is injected into the postcombustion flue gas stream. The injected NH3 or vaporized urea reacts with the NOx in the gas

stream within an optimal temperature range to form molecular nitrogen and water. There are a

number of design and operational factors that affect the performance of an SNCR system and

determine its technically feasible application to the 10" Walking Beam Furnace or the Bloom

Reheat Furnace. Factors relating to the viability of SNCR include:

• Reaction temperature range,

• Residence time available in the optimum temperature range,

• Degree ofreagent and combustion gas mixing,

• Uncontrolled NOx concentration level,

• Molar ratio ofinjected reagent to uncontrolled NOx, and

• Ammonia slip.

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The most important ofthese factors are the reaction temperature range and the

uncontrolled NOx concentration level. In SNCR applications, the reagent is it1iected into the

furnace itself in order to achieve the high reaction temperatures required. It is assumed for

purposes ofthis study that the furnace volume would allow for adequate residence time (> 0.5

second) ofthe reagent and furnace flue gases in each zone. It is further assumed that adequate

reagent/flue gas mixing could be achieved within the furnace given proper injection nozzle

placement. Any issues with establishing an efficient molar ratio ofreagent to uncontrolled NO,

and the presence of ammonia slip are minimized by a stable furnace flue gas flow and consistent

NOx concentrations - which are both present in each furnace (P071 and P081).

The NOx reduction reaction only occurs within an optimal temperature range. Below this

range, the reagent passes through the furnace unreacted and is emitted as slip. Above the

reaction temperature range, the ammonia reagent will oxidize and create NO,. The ideal reaction

temperature range for ammonia-based systems is reported as 1,600 to 2,000°F. The ideal

reaction temperature range for urea-based systems is reported as 1,650 to 2,100°F. The exit gas

temperature, for both P071 and P081, is considerably lower than the optimal temperature

(approximately 750°F) since they are recuperative furnaces and recover heat from the exhaust

gases prior to entering the stack. To increase the gas stream temperature to the optimum range,

the recuperative feature ofP071 and P081 would need to be removed or bypassed and/or a

heating system would need to be installed to increase the exit gas temperature to above 1,600-

1,650°F. Neither ofthese options is reasonable or practical for P071 and P08!.

The concentration of uncontrolled NOx also affects the performance of an SNCR system.

Effective SNCR systems are typically designed for a minimum NOx concentration in the furnace

flue gas ofseveral hundred parts per million. The optimal reaction temperature range is directly

related to NO, concentration. The high-end ofthe reaction temperature range decreases as NOx

concentrations fall below 200-300 ppm. The EPA Air Pollution Control Cost Manual (2002)

includes Figure 1.5 that shows the effect on SNCR system nominal NOx control efficiency as a

function oftemperature. Figure 1.5 shows efficiency curves for three uncontrolled NOx

concentrations - 30 ppm, 70 ppm, and 200 ppm. Iffor example the 10' Walking Beam Furnace

and Bloom Reheat Furnace were not recuperative furnaces and their respective exhaust gases were

of optimal temperature, the low NOx concentration would render SNCR an ineffective control

technology. The average NO, concentrations for the past compliance tests were 32.3 ppm and

14

.,.
32.7 ppm for P07l and P08l, respectively. If a -35 ppm curve is projected onto Figure 1.5

between the 30 and 70 ppm curves, that curve would intersect the horizontal axis (0 pct. NO,

reduction efficiency) at about 1,950°F. Below 1,600°F, SNCR is not applicable.

I I I

...... ·30 ppm I

.--r I

--70ppm .....V "'- !

20.0 ppm /' ---- I

I ./V-

----- 1(/

"" I

I - •. ~.. I I

-~ I ..... ' " I

·------I--I---~r-·;-~·T~-. ,

70

60

.f 50

.. 40

w

30

.g

&1 20

O·

z 10

o

1500 1600 1700 1800 1900 2000 2100

Terrperature (oF)

Figure 1.5: Effect ofUncontrolledNOxLevel onNOx Reduction Efficiency

The EPA Air Pollution Control Cost Manual (EPA OAQPS, EPA-452/B-02-001, January 2002).

15
TABLE 3. ALTERNATIVE NOx CONTROL STRATEGIES AND

THEIR APPLICABILITY TO REHEAT FURNACES

Applicability

NO, Control Alternatives P07l P081 Comments

Low NOx burners are already in use. NOx

Current Current concentrations for P07l range from 38 to 50

Low-NOx Burners Tecbnology Technology ppm with a pennit limit ofO.15lb

(RACT) (RACT) NO,/MMBtu and for P081 range from 32 to 95

with a pennit limit of 0.132 Ib/MMBtu.

Close coupled or separated over- NA NA Generally applicable to boilers not steel reheat

fire ports furnaces

P07l and P081 are both recuperative furnaees

Flue gas recirculation NA NA and recover the heat from the exhaust gases to

raise combustion air temperatures and lower

fuel use and associated NOx emissions.

Burners out ofservice NA NA Generally applicable to boilers and could lead

to uneven temperature profiles.

Steam/water injection NA NA Generally applicable to boilers and could lead

to uneven temperature profiles.

Dry low-NO, Burners NA NA Special burners typieally used for gas turbines

Ignition timing retard NA NA Applicable to internal combustion engines

Separate circuit after-cooling NA NA Applicable to internal combustion engines

Fuel emulsification NA NA Applicable to liquid fuels not to natural gas

fired sources

Poteutially Potentially Exhaust gas stream temperature too low and to

Selective noncatalytic reduction Applicable Applicable apply SNCR, the gas stream would need to be

heated above 1,650 OF

Nonselective catalytic reduction NA NA Applied to oxygen deficient gas streams

Selective catalytic reduction using Potentially Potentially urea, ammonia and methane as Applicable Applicable Not cost-effective application for P07I, P081

reducing agents

Incineration NA NA Not applicable to reheat furnaces

Scrubbing NA NA Not applicable to reheat furnaces

Process Modification NA NA Not applicable to reheat furnaces

Fuel switching NA NA Not applicable to gas-fired reheat furnaces

Temperature profile is critical in reheat

Adjustment ofair/gas ratio NA NA furnace, excess air is currently controlled to

optimum level

Potentially Potentially Temperature profile is ctitical in reheat

Low excess air Applicable Applicable furnace, excess air is currently controlled to

optimum level

Gaseous fuels reburn NA NA Not applicable to reheat furnaces

Oxyfuel burners Potentially Potentially Not cost effective Applicable Applicable

16
2.5 NOx RACT CONCLUSION

RACT forNOx emissions for the 10" Walking Beam Furnace and the Bloom Reheat

Furnace is the continued operation ofthe existing low-NOx burners. Republic proposes to

maintain the current Title V permit allowable NOx limits; i.e., 0.15 Ib/MMBtu for PO?I and

0.132Ib/MMBtu for P08!. The performance ofthe burners in the two furnaces in recent

compliance tests supports this consideration.

Combustion modification techniques such as LEA and flue gas recirculation have

operational drawbacks that could adversely affect furnace temperature profiles and cause uneven

steel heating. For this reason, these technologies are not "technically feasible" for either source.

The installation of Oxy-fuel burners would result in minimal NOx reduction at an excessive cost

thus it is also not considered RACT for these sources.

The use ofreasonably available add-on NOx control technology (SCR and SNCR) was

found to be either cost-prohibitive or technically infeasible owing to insufficient furnace exhaust

gas temperature and NOx concentrations. Retrofit SCRs systems are not cost-effective for either

furnace and SNCR is not technically feasible because the furnace exhaust gas temperatures are

significantly less than the effective operating range for this technology.

17