# Article VI Technical Support

# Lorain Plant ReasonablyAvailableControl Technology- NOx

# Emissions
Preparedby: Environmental Quality Management, Inc. 1800 Carillon Boulevard Cincinnati, OR 45240-2788 Prepared for: Republic EngineeredProducts

- LorainPlant 1807 East 28th 

# Street Lorain, OR 44055-1883 

# Submitted to the Ohio Environmental Protection Agency, Northeast District Office
December 22, 2008 '1'**:~**



### ••

### 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 otherthan an industrial boiler, stationary combustion turbine, or stationary internal combustion engine the owner or operatoris requiredby 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 Plantthatrequire a RACT study are the 10" Walking Beam Furnace (Emissions Unit P07l) and the Bloom ReheatFuruace (Emissions Unit P08l). EmissionUnits P07l and P08l are both recuperative-style reheat furnaces that currently employ 10w-NOxburnertechnology. 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-NOxburners and corresponding emission limits were mandated by consent decree. The NOx RACT analysis for the 10" Walking BeamFuruace 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. Forthis 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 itis also not considered RACT for these sources. The add-on control technologies evaluated (SCR and SNCR) also do notrepresent 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-NOxburners at the currentNOx emission limits from Republic's Title V permit ofO.15Ib/MMBtu for P07l and 0.1321b1MMBtu for P081.

11TABLE 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 BeamFurnace and BloomReheat Furnace 6 2.1 Emission Unit Description 6 2.1.1 10" Walking BeamFurnace (P071) 6 2.1.2 Bloom ReheatFurnace (P081) 7 2.2 Case-by-Case NOx RACT Determination 8 2.3 Combustion Control Techniques 8 2.3.1 Low NOxBurners 

### 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 NOxRACT Conclusion 16

111SECTION 1 

### INTRODUCTION
1.1 BACKGROUND Ohio Administrative Code (OAC) rule 3745-110-03(1) requires an owner oroperatorof affected existing sources otherthan 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 mustbe submittedto Ohio EPA's Northeast District Office on orbefore December 22, 2008. Sources owned by the Republic Engineered Products, Inc. (Republic) Lorain Plantthat require a NOx RACT study are the 10" Walking BeamFurnace (P071) and the Bloom Reheat Furnace (P081). This report satisfies that requirement.


### 1.2 SOURCE DESCRIPTION Republic Engineered Products, Inc. (Republic) operates a hotrolled barplantin Lorain, Ohio. The plant is located at 1807 East 28th Street and operates under the Title V permitfor Facility ID: 02-47-08-0299 effective June 20, 2003 (apermitrenewal application has been submitted to Ohio EPA). The standard industrial classification code numberthat is applicable to this facility is 3312

- BlastFurnaces and Steel Mills. Figure I shows the location ofthe 10" Walking BeamFurnace and the Bloom Reheat Furnace atRepublic's Lorain Plant. The operator's representative within the company who is the contactperson 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

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

2**~.**The Lorain Plantis a major stationary source for NOxemissions. Republic operates two NOx emission units that are applicable to this RACT study:

• Emissions Unit: P071 10" Walking BeamFurnace

• Emissions Unit: P081 BloomReheatFurnace


### 1.3 AFFECTED EMISSION UNITS The 10" Walking BeamFurnace and the Bloom Reheat Furnace are each subjectto 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 BeamFurnace (P071) is a recuperative furnace thatreheats up to 2,064 tons per day ofsteel billets from ambienttemperature 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/orheat 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 heatrecovery combustion system (the hot exhaust gases are used to heat the incoming combustion air in an indirect air-to-airheat exchanger orrecuperator). The furnace is fired by 75 low NOxburners located in five heating zones (three top zones and two bottom zones). Table I presents the design and operating parameters pertinentto this NOxRACT study requiredby 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 eightheating zones (four top zones, three bottom zones, and one screen zone). Table 2 presents the design and operating parameters pertinentto 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).

3 

### "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 ofBumers 75 75 75 Design
NO" Concentration, ppm 38.2 38.72 48.74 StackTest NO, Emissions, lb/MMBtu 0.095 0.097 0.093 StackTest Oxygen Concentration in Stack 12.09 12.13 9.45 StackTest 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
NOxEmissions, TPY 32.34 33.32 27.37 Fee Report
ExhaustFlow Rate, acfm 102,935 102,935 102,935 12114/2005 StackTest Temperature, OF 744 744 744 12/]4/2005 StackTest 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 inputand 24 hr/day operation Annual NOx Emissions, TPY 32.34 33.32 27.37 Fee Report

4

### 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 1,030Btu/cf MMCF/hr Number ofBurners 55 55 55 Design
NOx Concentration, ppm 32.71 93.28 67.93 StackTest NO, Emissions, Ib/MMBtu 0.044' 0.127 0.111 StackTest Production, tons 622,026 642,244 497,262 Fee Report Oxygen Concentration in Stack 4.65 4.87 7.56 StackTest 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
NOxEmissions, TPY 56.784 54.211 53.590 Fee Report ExhaustFlow Rate, aefm 216,987 216,987 216,987 Ratio P0811P071 heatinputs and P071 exhaust gas flow Temperature, OF 744 744 744 Basedon P071 Exit gas Temperature Title VPermitLimit, 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 NOxEmissions, 344 329 325 Based on 330 days of Ib/day operation peryear 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 stacktestperformed on Apnl 8, 2008 as follow-up to stacktestperformed on November 13,2007 that showed an average NOx 

### emission rate ofO.l411b perMMBtu (98.34 ppm).
5

### SECTION 2 NO, RACT FORTHE 10" WALKlNG BEAM FURNACE AND THE BLOOM REHEAT FURNACE
2.1 EMISSION UNIT DESCRIPTIONS The 10" Walking BeamFurnace (P071) and the BloomReheat Furnace (P081) are recuperative-style steel reheat furnaces. These furnaces will be described separately butthe 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 BeamFurnace is a recuperative furnace thatreheats up to 2,064 tons per day ofsteel billets from ambient temperature to 2, 100°F. The combustion system is designed for the use ofnatural gas only. The furnace was installed in 1995 as part ofa consent decree. 

### See U.S. v. 

### USSIKOBESteel 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 permillionBTU. Emissions Unit P071 is a five-combustion
zone walking-beam furnace thatburns natural gas as the primary fuel. The furnace has a combined heat input capacity from a total of75 burners of206 MMBtu/hr. The primary combustion zones are the soak, heat, and preheat zones and are further divided as follows:

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

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

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

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

• ten 5 MMBtu/hrin the bottompreheat zone (50 MMBtu/hr).
The 10" Walking Beam Furnace is a recuperative furnace, meaning that the combustion air is preheated with furnace exhaustgases in a recuperator. The burners are a low-NOxburner ,design and were manufactured by the NorthAmerican Manufacturing Company. These recuperative burners have a standard low-NOx design utilizing flame configuration and baffling to reduce NOx generation withoutrestricting heat transfer or fuel economy. The burners have a



### 6NO, rating ofno greaterthan 0.15 Ib NOxperMMBtu heat input and comply with the Title V pennitrequirement of0.15 lb NO, perMMBtu 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 ReheatFurnace (P081) is arecuperative furnace thatreheats up to 4,080 tons per day ofsteel blooms from ambienttemperature to 2, 100°F. The combustion system is designed for the use ofnatural gas only. This furnace was also installed in 1995 as partthe USS/KOBE consent decree. See 

# u.s. v. USSIKOBESteel 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 of0.132 lbs NOx permillion BTU. The system was subsequently upgraded in 1999 through the modification ofthe fuelsupply from mixed gas to natural gas allowing a reduction ofexcess airto 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 of55 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/hrburners in the easttop soak zone 

### (9MMBtu/hr),

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

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

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

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

• eight 13.75 MMBtu/hrburners in the bottomheat zone (110 MMBtu/hr),

• six 16.66 MMBtulhrburners in the bottomheat zone (100 MMBtulhr), and

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

7The BloomReheat Furnace is a recuperative furnace, meaning that the combustion air is preheated with furnace exbaust gases in a recuperator. The burners are a 10w-NOxburner 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 tbatminimizes their contactin the burnerport. The burners have an overall NOx rating ofno greater than O.l321b NOxperMMBtu heat input and comply with the Title V pennitrequirement of0.132 Ib NOxper 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 Documentthat we assessed is the use ofoxy-fuel burners. Available post-combustion add-onNOx control technologies potentially applicable to steel reheat furnaces include selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR). There are several otherNOx 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 notconsidered because both furnaces are recuperative furnaces and FGR is not

8applicable 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 NOxby controlling flame temperature, oxygen concentration, or othercombustionparameters. BothEmissions Units P071 and P081 currently employ low NOxburners which were installed as part ofa consent decree. 

### See U.S. v. 

### USSIKOBE Steel Co., Civ. ActionNo. I:92CVI928 (N.D. Ohio 1992). Based on the mostrecent stacktest forboth 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 currentemissions 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 limitusing EPA Method 7E procedures on an annual basis in accordance with the Title V Permitrequirements. The continued operation ofthe existing Low-NOx burners is considered RACT forboth sources.
2.3.2 Low 

### Excess Air Low excess air is a combustion modification technique in which NOx formation is inhibitedby reducing the amount ofexcess air used for fuel combustion to less than normal ratios. This technique lowers the flame-zone oxygen concentrationreducing thermal and fuel NOx formation. Typical excess airratios 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 limitedby the technology's potential to increase smoke (visible emissions) and carbon monoxide (CO) emissions. Ifinsufficientcombustion 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



### 9 

# '. "',temperatures would adversely affectbilletreheating and the quality ofRepublic's rolled steel products. Low excess air is not considered RACT for eitherthe 10" Walking BeamFurnace orthe Bloom Reheat Furnace. The 10" Walking Beam Furnace normally operates at about 20-40 percent excess air and the BloomReheat Furnace operates atabout 10-30 percentexcess air at the burner during operation. Republic Lorain has developed furnace operating experience at these current excess airratios such that the billets orblooms are reheated properly andproduct quality specifications are consistently met. The potential drawbacks to lowering the excess air rate in the furnace (e.g., lower efficiency, uneven billetreheating, increased smoke and CO emissions) do notjustifY further consideration ofLEA as RACT.

2.3.3 Oxy-Fuel Burners The use ofoxy-fuel burners is a combustion modification technique in which NO, formation is reduced by using oxygen gas to replace all orpart ofthe combustion air through burners designed to burn oxygen gas for fuel combustion. This reducesthe amount ofnitrogen in the combustion air stream. A drawback to this technology is that small deviations from operating parameters can result in significantNOx emissions. See L. Arvidsson et. aI., Oxy-Fuel

- Demanding butHighly 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 ofoxy-fuel combustion to the 10" Walking Beam Furnace and the Bloom Reheat Furnace would require burnerreplacement 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 notbe economicallyjustifiedto 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 ofoxy-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-NOxburners currently provide. See P. Fredriksson et.

10a!., 

### Application of Oxyfuel Combustion in Reheating at Ovako Hofors Works, Sweden

- Background, Solutions andResults, Steel Rolling (Paris 2006) (stating that conventional oxy-fuel combustion would reduce the NO, emissions to less than 0.10 Ib/MMBtu). The mostrecent stacktest for the 10" Walking Beam Furnace showed NOxemissions ofO.0951b NOjMMBtu and the NOxstacktest for the Bloom Reheat Furnace showed emissions ofO.0441b NOjMMBtu (NOTE: other stacktests for P081.have shown NOxemissions closer to the permitted limit of0.132 Ib NOx/MMBtu) which are comparable to the expected emissions for oxy-fuel combustion. The application ofoxy-fuel burners is not RACT for either the 10" Walking BeamFurnace or the Bloom ReheatFurnace. The costof purchasing and installing oxy-fuel burners and supplying oxygen to the reheat furnaces cannotbe justifiedfor little to no NO, reduction beyond what the low NO, burners currently accomplish. These factors do notjustify further consideration ofoxy-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 ofSCR and SNCR systems evaluated for applicability to the BilletReheat Furnace
were taken from The EPA AirPollution Control CostManual (EPA OAQPS, EP

### A-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 ofa catalystreactor bed. The injected NH) reacts with the NO, in the gas stream on the surface ofthe catalystto form molecularnitrogen 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 of675 to 1,OOO°F.

IIProperly 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 BloomReheat Furnaces operate continuously and thus offer arelatively 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 ofan SCR system, however, is generally higher than the cost ofotherNOx control systems. A budgetary cost estimate ofthe minimum capital and annual cost ofthe system shows that an SCR installed on eitherthe 10" Walking BeamFurnace orthe Bloom Reheat Furnace is not cost effective forremoval ofNOxfrom these sources. The EPA Air Pollution Control CostManual (EPA OAQPS, EPA-452/B-02-001, January 2002) estimates that the installed capital cost ofan SCR systemto be $4,000 to $6,000 perMMBtu/hrfor small oil and gas-fired units to over $10,000 perMMBtu/hrfor large coal-fired units in 1997 dollars. Installing an SCR system on eitherEmissions Unit P071 orP08l wouldbe aretrofit installation
so the installed costfor an SCR on these furnaces would be at least $10,000 per MMBtu/hrin 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 ReheatFurnace. At least 20 percent ofthe system's costwould be the catalystthatwould need tobe replaced approximately every 3 years. To estimate the annual capital recovery factor, in dollars, for an SCR system, a three year catalystlife will be assumed and a 10 year life for the otherinstalled equipment. These costs as well as the cost effectiveness ofNOxremoval are summarized as follows:

CostItem Total Capital Cost Equipment Cost (80%) CatalystCost (20%) 

## pon, $: 2,060,000 1,648,000

412,000 

### POSt, $: 4,216,000 3,373,000

843,000 Annual CostRecovery is based on a 10 year life for equipment other than the catalyst, a 3 year life for the catalyst and 10 percentinterest. The costrecovery factor for the equipmentis 16.27 percent for the equipment and 40.2 percent for the catalyst. An 80 percentNOxremoval efficiency is assumed to calculate cost effectiveness. The annual costs do not include process

• All values reported in 1997 dollars.
12operating costs, ammonia or other chemicals, maintenance, or otherrecurring costs that are normally included in a more rigorous cost estimate.

Estimated NOxRemoved. 25,9 tons CostItem 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 perton ofNOxremoved basis. The simplified and conservative cost estimate above shows that SCR control ofNOx on eitherthe 10" Walking BeamFurnace orthe Bloom ReheatFurnace 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) orliquid 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 ofdesign and operational factors that affect the performance ofan SNCR system and determine its technically feasible application to the 10" Walking BeamFurnace orthe Bloom ReheatFurnace. Factors relating to the viability ofSNCRinclude:

• Reaction temperature range,

• Residence time available in the optimum temperature range,

• Degree ofreagent and combustion gas mixing,

• Uncontrolled NOx concentration level,

• Molarratio ofinjected reagent to uncontrolled NOx, and

• Ammonia slip.
13The most important ofthese factors are the reaction temperature range and the uncontrolledNOx concentration level. In SNCR applications, the reagent is it1iected into the furnace itselfin orderto 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 givenproperinjection nozzle placement. Any issues with establishing an efficient molarratio ofreagent to uncontrolled NO, and the presence ofammonia slip are minimizedby a stable furnace flue gas flow and consistent NOx concentrations

- which are both presentin each furnace (P071 and P081). The NOxreduction reaction only occurs within an optimal temperature range. Below this range, the reagentpasses through the furnace unreacted and is emitted as slip. Above the reaction temperature range, the ammonia reagentwill 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 optimumrange, the recuperative feature ofP071 and P081 wouldneed to be removed orbypassed and/ora 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 orpractical for P071 and P08!. The concentration ofuncontrolledNOx also affects the performance ofan 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 ofoptimal temperature, the low NOx concentration would render SNCR an ineffective control technology. The averageNO, concentrations for the past compliance tests were 32.3 ppm and

14 

# .,.

### 32.7 ppm for P07l and P08l, respectively. Ifa -35 ppm curve is projected onto Figure 1.5 between the 30 and 70 ppm curves, that curve would intersectthe horizontal axis (0 pct. 

### NO, reduction efficiency) at about 1,950°F. Below 1,600°F, SNCRis not applicable.


## I 

# I I

...... ·30 ppm 

### I .--r I --70 ppm 

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



### 15

### TABLE 3. ALTERNATIVE NOx CONTROL STRATEGIES AND THEIRAPPLICABILITY TO REHEAT FURNACES Applicability NO, Control Alternatives P07l P081 Comments Low NOxburners are already in use. NOx Current Current concentrations for P07l range from 38 to 50 Low-NOx Burners Tecbnology Technology ppm with apennit limit ofO.15lb (RACT) (RACT) NO,/MMBtu and for P081 range from 32 to 95 with a pennit limit of0.132 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 andrecover the heatfrom the exhaust gases to raise combustion airtemperatures and lower fuel use and associated NOx emissions. Burners out ofservice NA NA Generally applicableto 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 Applicableto internal combustion engines Fuel emulsification NA NA Applicable to liquid fuels not to natural gas fired sources Poteutially Potentially Exhaust gas stream temperaturetoo 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 applicableto 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 applicableto reheat furnaces Oxyfuel burners Potentially Potentially Not cost effective Applicable Applicable


### 16

### 2.5 NO

### x RACT CONCLUSION RACT forNOx emissions for the 10" Walking BeamFurnace and the Bloom Reheat Furnace is the continued operation ofthe existing low-NOx burners. Republic proposes to maintain the currentTitle 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. Forthis reason, these technologies are not "technically feasible" for either source. The installation ofOxy-fuel burners would result in minimal NOx reduction at an excessive cost thus itis also not considered RACT for these sources. The use ofreasonably available add-on NOx control technology (SCR and SNCR) was found to be eithercost-prohibitive ortechnically 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.

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