North Carolina Department of Environment and Natural Resources 

Division of Air Quality 

Beverly Eaves Perdue 

Governor 

Sheila C. Holrnan 

Director 

February 7,201 1 

Gwen Keyes Fleming 

Regional Administrator 

USEPA Region 4 

Atlanta Federal Center 

6 1 Forsyth Street, SW 

Atlanta, GA 30303-8960 

Dee Freeman 

Secretary 

Dear Ms. Fleming: 

In response to your stafrs request for additional information with respect to the North Carolina 

Regional Haze State Implementation Plan (SIP), please find attached a copy of the reasonable progress 

analysis prepared by PCS Phosphate (PCS) located in Aurora, North Carolina, for the two sulfuric acid 

plants S-5 and S-6. 

The North Carolina Division of Air Quality (NCDAQ) received the analysis on October 8, 2010. 

In the analysis, PCS evaluated the technical and economic feasibility of various options for reducing 

sulfur dioxide (SO2) emissions from the plants, including replacement of the existing vanadium catalyst 

in the fourth and final catalyst beds with cesium-promoted catalyst. The evaluations are based on 

information provided by MECS, Lnc., a company that designs sulfuric acid plants. Design and cost 

information provided by MECS, Inc. is included in Appendix A of the attachment. The most costeffective control scenarios PCS identified in its analysis are summarized below: 

Sulfuric Acid Plant S-5 is currently only using about 90% of its catalyst load capacity. The plant 

can reduce the SO2 emission rate from 3.8 1 pounds per ton (lbslton) acid (the highest 3-hour average 

emission rate from 2009) to 3.5 lbslton acid by increasing the actual amount of vanadium catalyst in 

Beds 1-3 and replacing the catalyst in Bed 4 with cesium-promoted catalyst. Under this scenario, PCS 

can maintain the existing SOz strength (1 1.5%) in the converter inlet stream so that there is no 

production penalty. Acid production increases slightly due to improved SO2 conversion. This scenario 

would result in an SO2 emissions reduction of 165 tons S021year at an estimated cost of $3,456/ton. 

Table 4 of the PCS submittal provides a cost analysis of this scenario. The NCDAQ re-evaluated the 

cost of control with minor changes, including elimination of the costs of administration, property taxes, 

and insurance. The revised cost of control was estimated to be $2,879/ton. 

Sulfuric Acid Plant S-6 is currently using 100% of its catalyst load capacity. The plant can 

reduce the SO2 emission rate from 3.89 lbslton acid (the highest 3-hour average emission rate from 

2009) to 2.0 lbslton acid by replacing some of the vanadium catalyst in Beds 1-3 with fresh vanadium 

catalyst and replacing all of the catalyst in Bed 4 with cesium-promoted catalyst. PCS would have to 

reduce the SO2 strength in the converter from 1 1.5% to 10.5% to achieve the lower production rates, 

1641 Mait Serv~ce Center, Rale~gh, North Carolma 27699-1641 

2728 Capitat Blvd., Raleigh, Norih Carolina 27604 

Phone: 919-733-3340 I FAX 919-71 5-7175 I Internet: www.ncalr.org 

An Equal OpportunityIAffirmat~ve Actton Employer - 50% RecycledilO% Post Consumer Paper 
Ms. Fleming 

February 7,20 1 1 

Page 2 

which would result in a production penalty. This production penalty would be offset slightly due to 

improved SO2 conversion. This scenario would result in an SO2 emissions reduction of 1,I 11 tons 

S02lyear at an estimated cost of $1 1,414lton. Table 8 of the PCS submittal provides a cost analysis of 

this scenario. The NCDAQ re-evaluated the cost of control with minor changes, including elimination 

of the costs of administration, property taxes, and insurance. The revised cost of control was estimated 

to be $1 1,347lton. 

Currently, Swanquarter is below the glidepath for visibility improvement. As part of the 

reasonable progress analysis, PCS performed CALPUFF modeling to estimate the change in visibility 

that would occur at Swanquarter if the emission rates from both S-5 and S-6 were reduced from 4.0 Ibs 

S02/ton acid to 3.0 lbs S02/ton acid.' The average change in visibility was estimated to be 0.16 

deciviews for a 3-year period. This is far below the BART significance level of 0.5 deciviews. 

The cost of compliance estimates are higher than what the NCDAQ used in the Regional Haze 

SIP to determine if the cost was reasonable ($9 12 to $1,922 per ton of SO2 removed) for the 2018 

Reasonable Progress Goals. Therefore, the NCDAQ believes that the initial assessment for PCS 

continues to be valid; there are no cost-effective controls available for these units at this time within the 

cost threshold established for this reasonable progress assessment. The NCDAQ has notified the 

company that although additional controls are not being required this planning period, future-planning 

periods may require controls to be installed. 

If you have any questions regarding this information, please contact Laura Boothe at 

I,aura.Boot he @ ncdcnr. gov - or (9 19) 733- 1488 or Fern Paterson at Fern.Paterwn @ncdenr..gov or 

(9 19) 7 15-6242. 

Sincerely, 

%[. Shei a C. Holman 

Attachment 

cc: Michael Abraczinskas, NCDAQ 

Donald van der Vaart, NCDAQ 

Laura Boothe, NCDAQ 

Fern Paterson, NCDAQ 

Dick Schutt, USEPA 

Lynorae Benjamin, USEPA 

1 The reductions represented in the modeling (i.e., 1.0 Ihslton at both S-5 and S-6) are not identical to the reductions 

summarized in this memorandum (i.e., 0.31 Ibslton reduction at S-5 and 1.89 Ibslton reduction at S-6). Rather, the modeling 

is intended to show that changes in visibility resulting from the approximate SO2 reductions being evaluated are well below 

the significance level. 
PotashCorp" 

Helping Nature Provide 

October 5. 301 0 

PCS Phosphate - Aurora 

VIA FEDERAL EXPRESS 

Donald R. van der Vaart 

North Carolina Departnlent of Environnlent and fiatiiral Resources @%q, 

Divlsion of Air Quality $pi. %Y 

2733 Capital Boulevard Pa @$ 

Raleigh. NC 37604 w&p =?o@ 

"%.Q& -I lie: PCS Phosphdte Reasonable Progress Anaiysis 

Dear Dr. van der Vaart: 

As you requested. I have enclosed a copy of the independent reasonable progress control 

tecimoiogy evaluation of Sulhic Acid Planis 5 and 6 that PCS Phosphate Company, Inc. 

("PCS") conducted for the facility located near Aurora. North Carolina (the "Reasonable 

Progress Analysis"'). The attached Reasonable Progress Analysis differs from the anaiysis that 

was previously pro~ided lo you on July 15.201 0 in that: ji) predicted actual annual emission 

reductions were calculated as described in footnote jb) on page 1-2 of the Analysis: and iii) the 

cost eslimates used to calculate cosl effectiveness have been updated for consistency with the 

inforination provided to PC3 by MECS. This updated Reasonable Progress Analysis replaces 

the one previously provided to you. 

Tile Reasonable I'rogress Analys~s demoimrates that additiotlal controIs and/or switchmg 

catalysts are not cost effective. North Carolina has ample authority to require only cost effective 

measures in pursuit of the reasonable progress requirement of EPA's Regional Haze rules. 

Those rules assign North Carollna significant discretion to determine what nieasures to include 

in the Regional Haze SIP. EPA will have little choice but to approve a Regional Haze SIP that is 

based on a valid exercise of Xorth Carolinass discretion in weighing the relevant factors. 

I. Background 

Gnder the authority of the Clean Air Act I"CAA"j, the United States Environmental 

Protection Agency ("EPA") issued the "Regional Haze Regulations and Guidelines for Best 

Available Retroi3 techno log^. Derem~imions" (the '-Regional Haze Rule"). 70 Fed. Reg. 

39,104 (July 6, 2005j. The Regional I-Iaze Rule requires that certain states, including North 

Carolina, develop programs to assure "reasonable progress" toward a national goal of preventing 

any future: and remedying any existing. visibility impairment at nearly 156 federally protected 

parks and m~ilderness areas over an approximately fifty-year period. 42 U.S.C. 6 7491. 

- 

1530 NC Hy 306 South, Aurcra, NC USA 27806 T (252) 322-8266 ' 1252) 322-8061 

PES Phmphate Cwnpany, Inc ] www.potashcorp.com 
Donald R. van der Vaart 

October 5,301 0 

Page 2 

The Regional Haze Rule ft11t11er requires that certain sources of air pollutaiits itlstalI 

B,MT to control regulated emissions. 40 C.F.R. 5 5 1.302. Section 169-4 of the C.4A requires 

that states determine the appropriate level of' BART control by considering: (i j the tecl~nology 

available; (ii) theus OF con~pliance; jiii) the energy and non-air quality e~i~o~u~~~~t~~,ans 

of con~pliance: (iv) any existiiw ~ollutioi~ con~rol technoioa in use at the source; (-v) the 

remaining useful life of the source; and (vi j the degree of iniprcwsment in visibility that may 

reasonably be expected as a result of such technology. 40 C.F.R. 6 5 1.308(e)(l jCii)!A,l. The 

statutory factors in a reasonable progress a~ialysis are similar. They include: (i) the ~t of 

compliance; (ii) the time - nece,ssary for compliance; (iii) the energy and non-air quality 

envirorunental impacts of complia~zce: and iiv) the remainin_cusefid life of the emissions unit. 

46 C.F.R. 5 51.308(d)(l )(i)(A). 

Each unit must be uniquely evaluated uslng statutor? and regulatory factors in making 

BART and reasonable progress determinattons. EPA has recognized that. in considering the 

statutory factors. "States are frce to determine the welght and significance to be assigned to each 

factor." 70 Fed. Reg. at 339,130 The North Carolina Department of Environment and Natural 

Resources. Division of Air Quairty i "NCDENK-DAQ" ) has determined. and the enclosed 

Reasonable Progress AnaJysls suppons, that rt is nor cost effective to install additional controls 

and/or switch from vanadium to cesium catalyst in the final bed of Sulfuric Acid Plants No. 5 

and No. 6. 

The lack of cost effectiveness give? NCDEI\;K-DAQ ample authority not to require 

additional controls or catalyst replacement because, as noted above, cost is one of the sratutoq 

factors a State must consider in making BART and reasonable propss determinations. 

noted in the North -.------ Carolina --O---~-.-.---o--~- Renional Haze ...---. State ..-.. Implementation - --- .... Plan .._-,,-.._.--.--, submitted ..-_ .----_.. to EPA on 

December 17,2007. North Carolina will remain on t~~li&de~t,h~na~~r?~~$bility without --__ _ ,__ I--..--- "-,".-"-,--- 

re@&gadditio~zaI ~ontr_o&?_1:.~~~_c~$a~!;gre~J-~~lng~~-qd_the Staie. .- ---- not EPA, - ------- has the authority 

to make BART and reasonable progress determinations under the Regional Haze Rule. + _ .I--- -"..-.."-.-LI-.L------.-------"- ---, ".__I____"- ---. 

11. Technically Feasible ConlroI Technolotlies for SA Plants 1 and 2 Are Not Cost Effective 

The enclosed Reasonable Progress Analysis demonstrates that technically feasibie 

technologies far conrrolling SO2 enlissions from Sulfuric Acid Plants KO. 5 and 6 would cost in 

the range of $3.456 to $452,598 per ton of SO2 reduced. These teclmologizs are not cost 

effective. 

In the Reasonable Progress Analysis. PCS e~aluated all technically feasible control 

technologies. including replacing the existing vanadium with cesium catalyst in the final bed of 

the four-bed reacrors, at Sulftlric .4cid Plants No. 5 and No. 6 as required by the Regional Haze 

Rule. In one scenario exraluated b!, PCS for Sulfuric Acid Piant No. 6 (Scenario 1 j, an atmual 

emission reduction was assumed solelj- for purposes of calculating a cost effectiveness value. 
Doizald R. van der Vaart 

October 5, 3010 

Page 3 

For each ofthe evaluated scenarios: it would cost in the range of $3,436 to $26,484 per 

ton of SO2 reduced for SA Plant No. 5 and in the range of $I 1,4 14 to $452,598 per ton of SO? 

reduced for SA Plant No. 6 to inslall, operate and mainrain the evaluated technology. As 

detailed in the Reasonable Proyress Analysis, the cost effectiveness calculatiolls consider: (i) the 

cost of purchasing, installing. operating and maintaining cesium catalyst; (ii) the Iikely change in 

actual SO2 emissions tililt would occur with the ttse of cesium catalyst; and (iii) other costs, such 

as productio~l penalties and capital equipmeat costs. that would be assoc,iated with the use of the 

evaluated control tec1xiology. 

EPA has been clear that '-States have flexibility in how they calculate costs." 70 Fed. 

Reg at 39.2 1 7.39, I 53. Where possible, cost estimates should be conducted in accordance with 

the Office of Air Quality Planning and Smdard's ('-OAQPS") Cost Control Manual. 70 Fed. 

Reg at 39,166. AdditmnaIly, "[tfhe cost analysis should also take into account any site-specific 

design or other conditions . . . that affect the cost of a particular BART technology option." Id. 

PCS performed the cost estlmatcs m ~ts Reasonable Progress Analys~s in accordance with 

the OA QPS Cost Control Manual wh~le _talag ~ni~c~~~_sr>gclf~f&~ns. 

The Keasonable Progress Anal ysls demonstrates that the costs associated ~71th the iechnrcall y 

feasible control options at Plant\ 5 and 6 are unseasonably high in light of the actual enlission 

reductions, if an). that could be achieved 

PCS is aware that EPA lm evaluated canvenmg to cesium catalyst and has provided a 

different cost effectiveness calculation for thts scenario. The EPA calculatron does not include 

consideration of three cost elemer~ts that must be considered: (i ) average cost effectiveness using 

the full -- cost of re&aqgment of the current catalyst. (ii) production penalties, and (iii) capital 

..-- 

equipment costs. d L 

YCS. om the other kmd. evaluated a number of plant-specific scenarios under which the 

cesium catalyst would be replaccd in the final bed of the reactor to achieve EPA's target - emission rate. Ln each of these scenarios. PCS ~1_s&$_e-_c_o~o_21a~m_~7.~te~n~~arge of cesium -'.s.-7---.. 

cataiyst in determining .- ., averap-cost __." effectiveness. -,.-% _._-.-- EPA -.,- ca&uk~onk&$n-~ 

eJf$&.~eness of ce~~u~m,,.~~!~~yst-~~~t~.\~e.t~~,v~~adiun? ca_1.&1st. The EPA approach is wrong 

under its own guidance. Both average and incremental costs should be considered in any cost 

analysis. 70 Fed. Reg. at 39,127. 

: n 

EPA's use of only incremental costs underestimates the actuai cosrs that PCS wodd incur / in switching io cesium catalyst. PCS does not replace all of the catalyst in a hed unless there has -I._IXI__-_l_^l-,. -I--- '----*--'~-.---".-.14 -""... l,. ' ,.. 

I been _ ____ some _processjssue that has damaged tht. catalyst. PCS insread screens or scalps certain -- - ---- . . _"._. ..._ ' beds during 2-year t&narounds. ana%en adds new catalyst to the top of the bed to replace li~e 

lost quantity. The first beds. which have a h~giier duty than the final beds. are fully replaced over 

6 lo 8 years. The finai beds are replaced less frequentljr. 
Donald K. van der Vaart 

October 5. 3010 

Page 4 

EPA incorrectly assumes that both of the final beds require a whole new charge of 

catalyst and thcn calculalcs the differe~lce between the cosl of cesium catalyst and the cost of 

vanadium catalyst This 1s a false choice. The real choice is between the cost of two entirely 

new beds of cesium catalyst or the cost of replacing the port1011 of the vanadium catalyst bed that 

is screened during turnarounds. Therefore, the full cost of new beds of cesium catalyst should be 

included when est~lnating the average cost of control. This cost is reflected in the attached 

Analysis. 

The PCS cost effectiveness calcuiaiions acc.ount for- another factor that EPA missed in its, 

cafculation--a production penaitv that would be incurred if cesium catalyst is used with a lower 

SO2 gas stsen.gth to meet the lower emission levels. The OAQPS Cost Control Manual provides 

for consideration of this factor. -'In many systems, the insertion of a pollution control device 

causes the system to lose productive capacity. This can be caused by the device creating 

obstructions in the flue. temperame losses that create imbalances, or other physical changes that 

affect performance. These losses are collectively tenned 'parasitic power' losses." QAQPS 

Cost Control Maiual at 2-35 n.b. 

i 

A catalvst replacement can only achieve the lower emi&ossirafe advocated bj EPA when 

the plant is operated at the appropriate residence time for the cesium catalyst or sign31cant * 

capital equipment upgrades aqe_ulstdled. ----------I-Y__j- .eS. the necessary residence time can only be w.. 

aclueveah\.e~ucmg the feed rate. and hence. goduction rate~aa&ue&puurrurre_n~~ . I - --** - -eMachieve the desired res~'-ifs, a catalvst replacement will cause a lower production rate. NCDENRDAQ properly considered the ioss-in as part of tl~r cosl of compliance. EPA did not 

consider this factor at all 111 its cost effectiveness calcul~tion. 

/--7 

\ 

I As NCDENR-DAQ also notes: I'CS faces significant additional costs associated with the 

\ State's CIean Smokestack Act ("CSA"). PCS is the largest single consumer of electricity on the ! ' Progress Energy System and will bear- considerable additional costs through increased electricity I i rates resulting from compliance by Progress Energy wit11 the CSA. NCDENR-DAQ can 

1 coiisider these additional costs ii? determining what ineasures are reasonable to require in the 

!' Regional Haze SIP. L----- 

This discussion illustrates that PCS provided a complete and thorough evaluatron that 

considered all relevant factors while EPA ignored its own guidance to provide a results-oriented 

number. In addition to considering cost per ton of SO: controlled. the Regional Haze Rule also 

requires that NCDENR-DAQ consider the cost of control in relation to the visibilitjr 

improvements that are achievable 

- 

Per the NCDENR-DAQ SIP submiital. replacmg the exlsting vanadium pentoxide 

catalyst with ceslum catalyst ~tould result in oni) neghgible (ifany) visibil~ty improvement 

Calpufi'modeling of the plant was used to estiinate the assocxatecl change in deciviews from the 

current 4 0 lbiton W?SOJ to 2.0 Ibllon W2S01 The avcrage change was 0.16 deciviews for the 
Donald R. v,m den Vaan 

October 5,201 0 

Page 5 

covered three year period. Th~s change is far less than the 0.5 deciview significance level used 

in BART. and when coupled with the high costs associated with a catalyst conversion. leads to 

the conchion that thc conversion 1s not cost effect~ve for purposes of determining BART. 

111. North Carolina's SIP Complies with all Stan~torv Reqpirements 

As written. North Carolina's SIP complies with the Regional Haze Rule. and the State 

will remain on the glide path to natusal visibility by 2064 without requiring a catalyst 

replacexnent at the PCS Aurora facilih. 9, 

- +xqxxs-e's reasonab1e 

rate of prowess need onl~ be consistent with the statutory factors, not as fa2t as possible In the ^.pm 

final Conference agreement, Congress changed what had been the "maximum feasible progress" 

to "reasonable progress" when referring to the States' goals. H.R. REP. No 95-564 at 1536 

Thus. the State need not proceed at the masimuni rate feasible. 

EP.4 has recognized that "the CAA national visibility goal and 'reasonable progress' 

provisions do not mandate specific raws of progress, but instead call for 'reasonable progress' 

toward the ultimate goal of returning to natural backpound conditions." 64 Fed. Reg. 35,714. 

35,73 1 (July 1, 1999). States developing reasonable progress goals (,"RPGs") are directed to 

identify the ~rniform rate of progress necessary to attain natural back~ound conditions by 2064 

and then identify the amount of progress that would result if tile State achieved the uniform rate 

of progress during the period of the first regional haze implementation plan. The uniform rate of 

progress is the "default giide path." 70 Fed. Reg. at 39,143. 

t Once the glide path IS established, the State identiiies and analyzes the emissron control 

measures needed to achieve such progress for the period covered by the long-term strategy and 

cietem~ines whether those measures are leasonable based on the statutorj factors. 64 Fed. Reg. at 

35.732. -'ll'tlie State determines that the amounl of progress 1s reasonable based upon the 

statutory factors, the State sl-iould denl lily this amount of progress as its [WG] . . . unless it 

determines that addmonai progress is aIso reasonable " Id If additional plogress IS reasonable 

ku~cd on the ~/atutory ~LIC~OTJ. the State should adopt that amount of progress as ~ts RPG. Id 

(emphasis added). /- 

Here, NCDENR-DAQ has determined the uniform rate of progress necessary to achieve 

natural background conditions by 2064 and has andyed the statutory factors. The State has 

decided that the uniform ratc of progress is reasonable and achievable by 301 8 without requiring 

a catalyst replacement at the PC3 Aurora plant. NCDENR-DAQ rcjected additional controls at 

the Aurora facility as unreasonably costly after considering the statutory factors. NCDENRDAQ's co~iclusion is suppotred by PCS's own Keasonabk Progress .4nalysis. NCDENR-DAQ's 

BART and RPG detenl-iinstions are reasonable. and its SIP complies with the Regional Haze 

Rule. 
Donald R. van der Vmrt 

October 5.20 10 

Page 6 

I. North Carolina, hot EP-q. Has thc Authorin: to Determine BART and RPGs 

Tjnder the CAA. States. not the EPA, have authority to determine both BART and RPGs. 

Sec. e.g., 43 U.S.C. $6 7491(b)i2)(A) (sources subject to BART "shail procure, install, and 

operate, as expeditiously as practicable (and maintain thereafter) the [BART], as dedt.tcrmined 171: 

the Stuie (or the Administrator in the case of a plan promulgated under section 7410ic) of this 

title) . . . ."); 43 U.S.C. $5 7491 (g)(2) ("in deternlining [BART] the Stale (or the Administrator 

in determining cmission limitations which reflect such technology) shall take into consideration 

the costs of compliance. the energ>, and non-air quality eiwironmental impacts of compliance, 

any existing poIIution control technology in use at the source, the remaining useful life of the 

somce. and the degree of improvement in visibility which may reasonably be anticipated to 

result from the use of such technology.") (,en~phasis added). 

"The Haze Rule calls fcx states to play the lead role in designing and implementing 

regional haze programs." Am. Corn Growers 4ss 'n I*. E. PA.. 29 1 F.3d 1, 2 (D.C. Cir. 3002) 

(reversing portion of preiiminaq. Regional Haze Rule as '-inconsistent with the Act's provisions 

giving the states broad authority over HART determinatioi~s.")J Utilig: Air. Regulator?' Group I>. 

E.P.,4 .. 471 F.3d 1333, 1336 (D.C. Cis. 2006) (the second step in a BART determination 

"requires stum to determine the particular teclmology that an individual source 'subject to 

BART' must install.") (emphasis added). 

In addition to the stamtor> language and case law granting States broad authority to make 

BART determ~natious, the leyislat~ve history aiso supports this argument. For example. 

Congress' intent that States make BART deterlnlnations was evident in the Senate Debate 

adopting the Conference Agreement: 

Mr. h4cCiure: Gnder the conference agreement, does the State retain the sole 

authority for identificatioi; of sources for the purpose o-l'visibiiity issues under this 

section? 

Mr. Muskie: Yes; the State, not the Administrator, identifies a source that may 

impair visibilrty and thereby falls within the requirement of section 125. 

Mr. McClure: And does this also hold true for determination of "Best Available 

Retrofit Technologj."'? 

Mr. Muskie: Yes: here again it i~ the State which determines what constitu~es 

"Best Available Retrofit Tecl-tnoiogj,," as defined in section 128. . . . . 

123 CONG. REC. S 13696, S 1 3709 (1 977). EPA has even stated that "the State must detemiine 

the appropriate level of HART control for each source subject to BART," 70 Fed. Reg. at 

39,107. The Agency concedes that "[iln some cases, the State may determine that a source has 

already installed sufficiently stringent emission controis for compliance with other programs . . . 
Donald R. van der Vaart 

October 5. 20 10 

Page 7 

such that no additional controls would be needed f'or complimce with the BART requirement." 

64 Fed Reg. at 35.740. 

The State, not EPA has tile authority to make BART and RPG determinations. 

NCDENR-DAQ's determination of "no additiod control" is both reasoilabie and consistent 

with the CA4. 

PCS appreciates the opportunity to provide this inforn~ation to you. Please call Ross 

Smith at 252-372-8270 if you have an!; questions or if you require any additional infommtion. 

Sincerely. 

Steven A. Beckel 

General Manager 

Enclosure 

cc: Ross Smith, Manager. Environmental A-I-fairs 
FIWAL REPORT 

%- , .@. 

v %w 

REGIONAL HAZE RULE %$ @& 

*/A+ % r 

"C~A b 

REASONABLE PROGRESS 4% 

CONTROL TECHNOLOGY 

EVALUATION FOR SULFURIC 

ACID PLANTS NO. 5 AND NO. 6 

PCS PHOSPHATE COMPANY, INC. 

Prepared for: 

PCS Phosphate Company. Inc. 

1530 NC Highway 306 South 

Aurora, North Carolina 37806 

Prepared by: 

URS Corporation - North Carolina 

1600 Perimeter Park Drive, Suite 100 

Morrisville, North Carolina 27560 

i919! 461-1100 

URS Projecr No. 31877076 

October 5, 201 (1 
Section 1 Introduction ........................... .. ............................................................................ 1-1 

1 .1 Regulatory Background . . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . .. . . . . . 1 - 1 

1.2 Technical Conclusions ................. .. ............ .. .................................. ......... . 1-2 

1.3 Contact lnformation .... ............... .. ... .......... ................. ............................. 1-3 

Section 2 Reasonable Progress Analysis .....................................,.......,............................ 2-1 

2.1 hntroductian.. .. . . . . . . . . . .. . . ... . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 1 

7.1.1 Step 1 - Identify All Available Retrofit Control 

Technologies ...... ...................................... ............... .... .. ........ ..... .. 2-1 

2.1. Step 2 - Identify Technically Feasible Retrofit Control 

Technologies . . . . .. . . . . . . . .. . . . . . . . . . . . .. . .. . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 1 

2.1 Step 3 - Evaluate TecknicalIy Feasible Control 

Alternatives ..... ,.. .................... .. ....................................... . . 2-1 

1.1.4 Step 3 - Evaluate Calculated and Reported Impacts ................... 2-3 

2.2 RP Analysis for SA Plants Nos. 5 and 6 .................................................. 2-3 

2.2.1 '-3 Identify A11 Available Retrofit Control Technologies ....... .......... , 

3.2 Evaluation Cost Effectiveness of Control Scenarios ................... 2-6 

3.3.3 Conclusion ...... ... .................................. .... .................................. 2-1 1 

Table 1 : Summary of Sulfuric Acid Plant Parameters and Scenarios 

Table 2: Summary of Sulhric Acid Plant Control Cost Assessment 

Table 3: Scenario la - Cost Analysis for 3.8 lbiton HzS04 - SuIfuric Acid PIant No. 5 

Table 4: Scenario 1 - Cost Analysis for 3.5 Ib/ton H~SOL - Sulfiuic Acid Plant No. 5 

Table 5: Scenario 3 - Cost AnaIysis for 3.0 Iblton H2S04 (Includes Production Penalty) - 

Sulfunc Acid Plant lio. 5 

Table 6: Scenario 3 - Cost Analysis for 2.0 Ibiton H:S04 (Includes Capita1 Equipment) - 

Sulfuric Ac~d Plant No. 5 

Table 7: Scenario I - Cost Analysis for 3.5 Ibiton I&S04 - Sulfunc Acid Plant No. b 

Table 8: Scenario 2 - Cost Analysis for 3.0 Ib/ton HlS04 (Includes Production Penalty) - 

Sulfuric Acid Plant No. 6 

Table 9: Scenario 3 - Cost Analysis for 2.0 lb/ton H2SO;r (Includes Capital Equipment) - 

Sulfuric Acid Plant No. 6 

APPEMDIX A: MECS Design and Cost Information 
LIST OF ACRONYMS LID ABBREVUTIONS 

BACT 

DAQ 

DENR 

EPA 

H20 

H2SO4 

IbJton 

NH3 

NSPS 

02 

RBLC 

RP 

S 

S A 

SP 

SO: 

so3 

so4 

tQY 

US 

Best Available Coatrol Technology 

Division of Air Quality 

Department of Environment and ru'atural Resources 

Environmental Protection Agency 

Water 

Sulfuric Acid 

Pounds Per Ton 

Ammonia 

New Source Performance Standards 

Oxygen 

RACTIBACTfLAER Clearinghouse 

Reasonable Progress 

Sulfur 

Sulfuric Acid 

State Implementation Plan 

Sulfur Dioxide 

Sulfur Trioxide 

Sulfate 

Tons Per Year 

United States 
PCS Phosphate Company, hc. (PCS Phosphate) owns and operates a facility located m Aurora. 

Beauforl County. North Carolina. Beaufort County 1s located in the eastern coastal reglon of 

North Carolina. The PCS Phosphate Aurora facility falls under the standard North Amencan 

Industry CIassification System (WAICS) codes 212392 for phosphate rock rnming and 335312 

ibr phosphoric acid manufacturing 

Suihc acid (SA) is manufactured at the facility in order to react with phosphate rock and 

produce phosphoric acid. The sulfuric acid production area currently inchdes three sulfuric acid 

(Sh) plants (S.4 Plant No. 5. No. 6. and No. 7), one cogeneration plant, and one auxiliary boiler. 

SA Plant No. 5 began operation in 19E and SA Plant Kc. 6 began operation in 1985. SA Plant 

No. 7 began operation in 2010. The two older SA Piants No. 3 and No. 4 shutdown after SA 

Plant No. 7 began operation in 201 0. 

At the request of the North Carolina Division of Au Quality (NCDAQ), PCS Phosphate retained 

URS Corporation to prepare an air emission control technology evaluation for SA Plants No. 3 

and No. 6 consistent with the requirements of 40 CFR 5 1. Appendix Y. This report presents the 

results of the control technology evaluation. 

1.1 REGULATORY BACKGROUND 

The Clean Air Act (CAA) established goals for visibility in many national parks and wilderness 

areas. Through the 19?7 amendments to the CAA, Congress set a national goal for visibility as 

"the prevention of any future, and the remedying of any existing, impairment of visibility in 

mandatory Class I Federal areas which impairment results from manmade air pollution." The 

CAA amendments of 1390 required EPA to take regulatory action on regional haze and on July 

1, 1999. EPA promulgated the final Regional Haze Regulation. The final Reponai Haze 

Regulation calls for state and federal agencies to work together to @rove visibility in 

I56 national parks and wilderness areas in the United States by developing and implementing 

long-tern air quality protection plans to reduce the pollution that causes visibility impairment in 

these protected areas. 

The Regional Haze Regulation provides States flexibility in determining reasonable progress 

goals for protected areas by conducting certain analyses to ensure that they consider the 

possibility of setting an ambitious reasonable progress goal, one that is aimed at reaching natural 

background conditions by the year 2064. The regulation requires States to establish goals for 

each affected area. 

The Regional Haze replation also requires States to develop long-term strategies including 

enforceable measures designed to meet reasonabie progress goals. The first long-term strategy 

will cover 10 to 15 years. with reassessment and revision of those goals and snategies in 201 8 

and every 10 years thereafter. State strategies will address their contribution to visibilinr 

problems in Class 1 areas both within and outside the State. States were required to develop and 

submit Regional Haze State Implementation Plans (SIPS) by the end of 2007. These included 

Best Available Retrofit Technology (BART) evaluations for emission units that began operation 

between 1962. and 1977 as well as reasonable progress evaluations for other emission units. 

In December 2007, the NCDAQ subwtted a ReglonaI Haze SIP to the LTS EPA, Reyon 3 for 

the~review and approval. As part of the SLP submttal. the NCDAQ ~ncluded a reasonable 

progress (RP) control technology evaluation for several emlsslon umts located In North Carohna 

1-1 
including the SA Plants No. 5 and KO. 6 located at the PCS Phosphate facility. The NCDAQ 

evaluation concluded that further emission controls for the SA Plants KO. 5 and No. 6 were not 

cost effective and not reasonabIe at this time. 

During the EPA Region 4 review of the NCDAQ SIP, the EPA quesrioned the NCDAQ on their 

conclusions and asked whether further emission reductions could be achieved on SA Plants No. 

5 and No. 6 by replacing the vanadium catalyst in the final pass with cesium catalyst in order to 

reduce SO2 emission rates to a ievel of 2.0 lbsiton H2S04. On June 1,2010, the NCDAQ sent a 

lette~ to PCS Phosphate requesting that the company develop an independent RP control 

technolow evaluation for SA Plants No. 5 and KO. 6. Ln response to the NCDAQ request, PCS 

Phosphate retained URS Corporation to perform a RP control technology evaluation for SA 

Piants So. 5 and 6. The statutory factors that are required in evaluating reasonable progress for 

an emission unit include the costs. the time necessary for compliance. the remaining useful life 

of the facility, and the energy and non-air environmental impacts of the control installation. 

Consistent with the NCDAQ RP evaluation methodology contained in the North Carolina 

Regional Haze SIP, the cost of compliance was used as a screening tool to determine whether the 

emission units would require the full four-factor evaluation. The derails of the RP analysis and 

the concIusions reached are presented in this document. 

1.2 TECHNICAL CONCLUSIONS 

A detailed control technology evaluation was performed following the RP evaluation guidance in 

- 

b. The emmion reductions are based the percent reduction %om the maximum 3-hour emission rate in 2009 (Ibiton) 

to the larger emission rate (Ibiton) for each scenario rimes the maximum annual emisslon rate in past ten years 

(tonsiyr t. 

c. Based on the tocal annualized costs divided by the annual emission reciuction. 

40 CFR Part 5 1, Appendix Y. The following presents a summary of the RP evaluation cost 

effectiveness analyses for several emission reduction scenarios for the SA Plants No. 5 and No. 

6. 

Summary of Sulfuric Acid Plant Control E\7aluation 

Scenario la: Maximizing vanadium catalyst. 

Scenario 1 : Rlaxirn~ze vanadium catalyst and replace pass 4 with cesium cataly5t. 

Scenario 2: Maximize vanadium catalyst. replace pass 3 with ceslurn catalyst, and reduce SOz gas strength at the 

miet of the converter from 11 .% to 10.5%. 

Cost Effec*iveness 

(Yton) " 

$20.484 

S3.456 

$10.672 

Total Annualized Costs 

6&r) 

Capital Investment 

(%) 

r 

1 

I I Sulfuric Acid 

j Plant No. 5 

/ Scenario 

Ii I 2.U 1 062 I %16.543.W0 

i 1 I 

1 i 

I 

1 I e 3.8 5 

I 1 3.5 !6S 

I 1 2.0 ! 962 

I 

! 

Annual Emission I Annual Emission Target Reduction (tonlyr) Gb SOZlton Acid) j 

Si3.133.21 I $13.651 

1 

I 

z. Based on MECS SO? em~ssion limt guaranree on a contrnuous basis. 

$2:?.??(: 

$2.024.45 : 

$2,024,451 

Ji40.760 

$569,490 

SIC.266.485 
introduction 

Scenario 3: Maximize vanadium catalyst replace pass 4 with cesium catalyst, repiace existing comvener with a new 

48 k diarnercr converter, and repiace No 1 superheater to obtain optimum temperature in Pass 3. 

I 

1 Annual Emission Capital investment 

I Reduction jlon/yr) ($) 

I 

i i 

a. Based on ,WECS SOz emission hmjt guarantee on a continuous basis. 

b The ermsslon reductions are based the percent reduct~on from the nlaxlmum 3-hour emlsslon rate In 3009 (Ibltoni 

to the tdrget enxsslon rate ilbitont for each scenarlo times the max~mum annual em~sslon rate 111 pst [en years 

(tonstyr) 

c Based on the total annuahzed costs drvlded by the annual ernlsston reductmn 

Scenario 1 : Replace pass 3 with cesium catalyst and replace incremental amount of vanadium catalyst. 

Scenano 2: Replace pass 4 with cesim catalyst, and reduce SOZ gas strength at the inlet of the converter from 

11.5% to 10.5?~0. 

Scenano 3: Replace pass 4 with cesium catalyst and replace existing converter with a new 48 ft diameter converter 

,4s shown in the tables above. the cost effectiveness terms of capital investment and cost per ton 

of compound removed to achieve an SO? emission rate of 3.0 lb/ron H$OJ is higher than those 

that would be considered economically feasible for permitting under the EPA New Source 

Review Regulation for Best Available Control Technolojg [BACTj evaluations; the EPA 

Regional Haze Regulation for Best Available Retrofit Technology (BART) evaluations: and the 

criteria set forth by the NCDAQ in the Regional Haze SIP submittal. Therefore, the RP 

evaluation concludes that further emission reductions for SA Plants So. 5 and No. 6 are not cost 

effecrive and thus not reasonable for the purpose of Regional Haze reduction goals and confirms 

the conctusions contained in the NC Regional Haze SIP dated December 17,2007. Since no cost 

effective control measures were identified, the remaining three statutoly factors were not 

evaluated in this report. 

1.3 CONTACT INFORMATlON 

Should the NCDAQ have any questions or comments regarding this document, please contact 

Mr. Ross Smith of PCS Phosphate at ((252) 322-8270 or Mr. Randy Taylor of URS Corporation 

at (919) 461-1520. 
Reasonabte Progress 8nahfsis 

2.1 INTRODUCTION 

In performing the control technology evaluation, the following 4-step process used for Best 

Available Retrofit (BART) and RP evaluations were utilized to conduct the control evaluation as 

described in Appendix Y to 40 CFR 5 1. 

The four steps are: 

STEP i - Identify All Available Retrofit Control Technologies, 

e STEP 7, - Eliminate Technically Infeasible Options, 

STEP 3 - Evaluate Control Effectiveness of Remaining Control Technologies, and 

STEP 4 - Evaluate Impacts and Document the Results. 

Each of these steps is discussed in further detail in the sections presented below. 

2.1.1 Step 1 - Identify All Available Retrofit Control Technoiogies 

Appendix Y to 40 CFR 5 1 defines an available retrofit control option as an air pollution control 

technology with a practical potential for application to the emissions unit and the regulated 

compound under evaluation. Technologies available for compliance with Best Available Control 

Technology @ACT) or Lowest Achievable Emission Rate (LL4ERj regulations were included as 

part of the RP analysis. Furthermore, technologies that are evaluated should inctude exisiing 

controls for the source category in question as well as the transfer of controls that have been 

applied to similar source categories and gas streams. However, control technologies which have 

not yet been applied to full scale operations are not required to be inciuded in the evaluation. 

Potentially applicable control technologies can be grouped into one of three categories: 

Pollution Prevention. As stated in the regulation this is "use qf inherentl~s lower-emitting 

processewjx-actices, including he use of control techniques /e.g., /ow-NOx burners) and 

wot-k practices that prevent emisszons and result in lower '~rou'zaction-specrftc" ernlssions. " 

Add-on Control Technologies. "Use of {and where alrea$y in place, improvement in the 

pecformance ojj add-on controls, such as scrzrbbel-s,,fabi-ic,filters, rhemal oxidizers and 

other devices that conrroi and reduce emissions afte~ they are produced." 

Combinations of the previous two categories. 

Sources that were used to determine the potentially applicable control technologies for the PCS 

RP analysis include the Environmental Protection Agency's RACT.BACT/LAER Clearinghouse 

(RBLC). control technology vendors, informat~on from EPA consent decrees, and information 

from previous BACT analyses performed at the facility. 

2.1.2 Step 2 - Identify Technically Feasible Retrofit Control Technologies 

Step 1 of the RP analysis identifies all of the control technologies that are potentially available 

for the SA Plants No. 5 and No. 6. Ln step 2 of the analysis, ths list is further refined to include 
Ileasonable Progress; Wnafitsis 

only those technologies which are technically feasible. Appendix Y of 40 CFR 51 defines a 

technica1ly feasible control technology as follows: 

"Control technologies ar-e techrzical!t~.femibIe ?f either (1) the?, have been ir~talied ntld 

opevafed successfui(~*.for rhe &pe ofsource under review under srrniiar- conditions, or (2) 

the rechnoio~ could be uppized to the source under rakttl. Two kqv concepts are 

iinportanz in determining wizerher a rechnology could be applied "wniEnbifi~>" und 

"applicahili~,. " ... a technolop is considered "avai2ahie1' if the source owner mq obtain 

ir through cornrneiAcial cizar~nels. or it is otherwise available within the common sense 

meaning ojntbre term. An availabk technology is "upplicahie" ifit can reasonah(v Be 

ivrstalleci and opera~ed on the source ppe under consideration. A rechnoiogy that is 

mailable and applicable is technicai(~!.feasibie." 

Control technologies that are demed technically infeasible in this step of the evaluation must 

include specific data stating that the technology is either comrnercialIy unavailable or outline the 

specific circumstances which preclude its application. Facilities may demonstrate that a 

particular techndogy is infeasible due to "unresoivable technical di,!ficuities with applying the 

conrrol to the source (e.g., size of the uuit, location of the proposed site, operaring problems 

related to spectfic circu?mlarzces qf the smrrcc, space constraints, reliabiiihi, and advcrse side 

effects on the resf uf~he.facilityi." 

The implication of cost effectiveness is not included in ths step of the analysis. 

2.1.3 Step 3 - Evaluate Technically Feasible Cornlol Alternatives 

Control technologies determined to be ~echnically feasible in step 2 of the anahysis are further 

evaluated in srep 3. As stated in the regulation. the two main issues in step 2 of the process are 

as follows: 

Ensuring that the degree of control is evaluated using a metric that ensures an '.apples to 

apples" comparison of emissions performance levels among options, and 

Giving appropriate treatment and consideration of control techniques that can operate over a 

wide range of emission performance levels. 

The analysis is based on the maximum level of control that a technology is capable of achieving 

2.1.4 Ste~ 4 - Evaluate Calculated and Reported lrnpacts 

Appendix Y to 40 CFR 5 1 presents detailed insrructions for conducting the analysis of each 

potential impact. For the control technologies determined to be commercially available and 

techcally feasible. the following four stamtory factors that would porentially result &om the 

instaIIation of a conno1 technology are evaluated. 

lmpact analysis part 1 : Costs of compliance, 

lmpact analysis part 2: Energy impacts, 

* Impact analysis part 3: Non-air quaiity environmental impacts, and 

e Impact analysis part 4: Remaking useful life. 
SEl!l‘l@HTW O Reasonable fsrogress Anafysis 

Consistent with the NCDAQ W evaluation methodology contained in the North Carolina 

Regional Haze SIP, the cost of compliance was used as a screening tool to determine whether the 

emission units would require the full four-factor evaluation. 

2.2 RP ANALYSIS FOR SA PLANTS NOS. 5 AND 6 

The SA Plants Nos. 5 and 6 units already use the double absorption process to control SO2 and 

mist eliminators to control H2S04 mist (PMlo) to meet NSPS limits for SO2 and H2S04 mist. The 

principal steps in the sulfuric acid production process consist of burning sulfur (S) in air to form 

sutku dioxide (SOz), combining the sulfkr dioxide with oxygen (O?) to form sulfur trioxide 

(SO?), and combining the sulfur trioxide with water ('H20) to form a solution containing sulfuric 

acid (?&?SO4). 

Sulfur dioxide is formed when elemental sulfur is sprayed into a horizontal spray-type burner. 

the sulfur dioxide gas exits the burner compartment at a higher temperature than the optimum for 

conversion and it enters a heat recovery boiler to be cooled off. Upon exiting the recovery 

boiler, the sulfur dioxide rich gas enters the first converter where it is partially converted to SO,. 

Yet all the SOz is converted to SO;; the conversion into SO; is a function of the catalyst and 

oxygen present during the reaction. 

2.2.1 Identify All Available Retrofit Control Technoiogies 

As determined from recent BACT determinations for SO2 emissions from sulfunc acid plants, 

the prevalent control technology for SO2 emissions from sulfuric acid plants is a dual absorption 

system with a catalyst, which is employed at SA Plants Nos. 5 and 6. Other technologies have 

been identified as potentially applicable control technologies for SOz emissions from sulfuric 

acid plants. The following fechnologies are evaluated: 

Sodium SuEte-bisulfite scrubbing 

Regenerative Scrubbing 

Molecular sieve 

Ammonia Scrubbing 

Dual absorption process with cesium catalyst 

Sodium Sulfite-Bisulfite Scrubbing 

In the sodium sulfite-bisulfite scrubbing process, SO2 is removed by scrubbing the exhaust gases 

with a sodium sulfite soiution. The resulting sodium bisuIfite solution is fed to a heated 

crystallizer where sodium sulfite crystals are fom~ed with the release of SOz and water vapor. 

The crystals are separated from the mother liquor and dissolved in the recovered condensate for 

recycling to the absorber. The recovered wet SO: is recycled to the acid plant. In all processes 

employing sulfite-bisulfite absorpf on even without regeneration, some portion of the sulfite is 

oxidized to sulfate, from which SOz cannot be regenerated in the heating sequence. Ths sulfate 

must be purged from the system. Some thio-sulfate can also be formed in the process. The 

extent of oxidation is dependent on several factors (some whic'h may be difficult to control) such 

as the oxygen content of the gas stream, the temperature and residence time of the liquor in tne 

recovery sections, and the presence of conraminants that may act as oxidizing catalysts. The 
Reasonable Progress Aaabsis 

formation of oxides, which readily precipitate Erom solution. can result in plugging and 

operational probhns. Since promulgation of the NSPS for sulfuric acid manufacturing, only 

two piants have used the sodium sulfite-bisulfite control technoiogy. The sodium sulfitebisulfite system at one of the plants experienced operational difficulties and was subsequently 

replaced by an ammonia scrubber. The other plant is a part of an Arm); anmunition production 

faciliry and bas not been used since 1994. 

Sodium sulfite-bisulfite connol technology is rejected from further conslderalion in this analys~s 

because if has not been demonstrated commercially as provldrng reliable emissions controt of 

less than 1.0 lb SOzhon of 100 percent &SO4 produced at a sulfur-bumlng sulfuric acid 

manufacrurmg plant. SA Plants 5 and 6 are currently limited to 4.0 Ib SQiton &SO, by NSPS 

Subpart H. 

Regenerative Scrubbing 

In general, regeneratwe scrubbers absorb the compound to be removed In a liquid media whlch 1s 

then routed to a second vessei where the compound 1s recovered from the llquid med~a. The 

"cleaned" liquid media is routed for reuse and the compound removed can either be disposed of 

or possibly returned to the process. 

The technical feasibility of regeneratix scrubbing through a propfietaw process called 

UmluSolv@~ has been evaluated. Literature from CanSoTv@ provides the following process 

description: 

I. The feed gas is first quenched and saturated in a water pre scrubber. The pre scrubber 

des~gn is selected based on total solids and So3 content in the gas and the regulatory 

requirement to remove them 

2. The gas is then contacted with the lean amine solution in a counter-current column where 

SO1 is absorbed. The treated gas exits the absorber with an SO: content as low as I0 

ppmv, depending on design parameters. 

3. The SO:-rich amine from the absorption column 1s pumped to the regeneration coiulnn 

via leanirich arnine heat exchanger for energy recovery. 

4. The lean amine solution is regenerated by indirect steam strippmg and the SO? is 

recovered as a pure, water-saturated product, 

5. The lean amine leaves the stripper reboiler and is pumped back to the absorption column 

via the iew'rich amine heat exchanger and the lean alnine cooler. 

6. A slipstream of the arnine 1s purified to pre17ent accumuiatlon of heat stabie salts, 

7 The by-product SO. can be converted to vanous sulfur products such as liquid SO., 

sulfuric acid. or sulfur. 

The CanSolveGL website indicates that a regenerative scrubber unit has been instailed on a 

sulfuric acid plant operated by Conoco-Phillips at their Wilmington, California faciliv. The 

Wilmington operation is part of a refining operation split between Carson, California and 

IViirnington, California. The Carson site operates as the front end of the refining process, using 

high sulfur crude oil as the feedstock. The Wilmington, CaIifornia site operates as the back-end 

of the refining process upgrading the products. Overall. the site produces mostly transportation 

grade fuels such as gasoline. diesel, and jet fuel. The Wilmington plant is an acid regeneration 
Reasonable Progress Analysis 

facility and its operation is different from the sulfur burning operation at the Aurora facility. 

Emissions are inherently lower from an acid regeneration plant because the inlet gas 

concentration is lower (generally 1 ON), thereby, resulting in lower SO: emissions. Additionally, 

the oxygen and SO: concentrations may be controlled independently in the regeneration plant, 

allowing for better control and tower emissions. This type of control is not possible in a sulfur 

burning operation. Additionally, there will likely be degradation of the amine solution due to the 

acid mist in the exhaust stream. There will also be secondary increases in emissions of 

greenhouse gases because of the increased steam demand which will be achieved through the 

combustion of additional fossil heis. This technology was recently evaluated for the sulfuric 

acid plant at the PCS Geismar, Louisiana facility and it was determined to be technically 

infeasible due to potential operating difficulties and expected cost associated with operating the 

technology. EPA concurred with this conclusion for the Geismar sulfuric acid plant and focused 

on double absorption technology with cesium catalyst in the final pass as the preferred 

technology approach. 

Molecular Sieves 

This process utilizes a proprietary molecular sieve system in which SO: is adsorbed on synthetic 

zeolites. The adsorbed material is desorbed by purified hot tail gas from the operating system 

and sent back to the acid plant. Since the promulgation of the suffuric acid plant NSPS, only one 

new unit was built with a molecular sieve system to control SO2. However, exrensive 

operational difficulties with the system caused this piant to be retrofitted with a dual absorption 

system for SOz control. The dual absorption system was retrofitted in January 1979 and has 

operated satisfactorily since that time. 

Since molecuiar sieve control technology has not been commercially demonstrated and 

operational difficulties are anticipated, this option is considered technically mfeasibie for further 

reducing SO: emissions from S.4 Plants 5 and 6 and is rejected from further consideration. 

Ammonia Scrubbing 

The ammonia scrubbing process uses anhydrous ammonia (NH3) and make-up water in a twostaze scrubbing process to remove SOz. The typical SO: removal efficiency qf this control 

technoiogy is not as high as conventional dual absorption technology; however, several facilities 

in the U.S. have used this technology to meet the KSPS for sulfuric acid manufacturing plants. 

According to MKS. Inc., sulfur-burning suifuric acid manufacturing plants that have used 

ammonia scrubbing technology have applied the technoiogy as a retrofit to "existing" plants that 

were based on single absorption technology that had to improve emissions control to achieve the 

XSPS limit of 4.0 lb S02/ton of 100 percent H~SOS produced and comply with the more strmgent 

state limit of 3.8 lb S02/ton of 100 percent H2S04 produced. Due to operational difficulties and 

high costs associated with operating ammonia scrubbing systems, all but two single absorption 

piants using ammonia scrubbing technology have been shut down. and the two existing plants 

still in operatior, are required to meet the both the NSPS emission limit of4.0 lb S02/ton of 100 

percent E12S04 produced and the state limit of 3.8 lb Soziton of 100 percent. H2S04 produced. 

Consequently, ammonia scrubbing is rejected from this analysis because it is commercia11.y 

undemonstrated on dual absorption plants. because of operational difficulties that have been 

experienced by other sulfuric acid manufacturers, and because it is unknown whether additional 

control of SO: emissions would be achieved by a retrofit with this type of system. Furthermore. 

the ammonium sulfate ultimately emitted is a leading contributor to visibility impaiment of 
Federal Class I areas and would have adverse- impacts on the state's Reasonable Further Progress 

goals in the Regional Haze Program under the C,lean Air Act. Additionally, not all of the 

ammonia entering the scrubber would be consumed in the reactions described above. This 

would result in excess ammonia being emitted through the stack in a process termed "ammoniaslip." 

Duaf Absorption Process with Cesium Promoted Catalvst 

Dual absorption technology is widely accepted as BACT for sulfuric acid plants. ConceptuaIly, 

dual absorption is the addition of another converter and absorbing tower to the exhaust from a 

single absorption plant. Vanadium-based catalysts are used in virtually all existing dual 

absorption systems, including SA Plants Nos. 5 and 0. Cesium-promoted catalysts have recently 

been used, and can provide higher leveis of control. There are no by-products or waste 

scrubbing materials produced by the dual absorption process. Speni cataiyst is not treated as 

hazardous waste. The cesium-promoted catalyst was developed specifically for lower 

temperature operations which can lead to greater SO1 conversion and hence lower SO2 emissions 

to the atmosphere. The cesium salt promoter reduces thr required operating temperature for the 

sulfuric acid caralyst by as much as 40°C (70°F). Higher SO2 conversion is possible at tower 

temperatures as long as the catalyst is "active." The cesium-promoted catalysts are sufficiently 

active at these Iower temperatures (390 ro 410°Ci'735 to 770°F) to take advantage of this 

conversion "opportunity." Cesium catalyst is technically feasible and thus theoretical analyses 

based on this retrofit technology were perforined for SA Plants Nos. 5 and 6. 

2.2.2 Evaluation Cost Effectiveness of Control Scenarios 

A major component of the BART and RP evaiuations is the determination of the annual 

operating costs associated with a particular technology. In developing this evaluation: MECS 

was contacted to provide total capital investment costs associated with each scenario. ,4ppendix 

A presents the MECS design and cost information for several control scenarios. To estimate 

annual operating expenses, the EPA's Cost Control Manual was also used to complete the 

evaluation. For the SA Plants No. 5 and No. 6, a cost effectiveness evaluation was performed for 

several controI scenarios using cesium catalyst replacement in the final pass. MECS, Inc. 

provided four scenarios (la. 1, 2. and 3) for SA Plant No. 5 and three scenarios (1.3. and 3) for 

SA Plant Yo. 6. The following presents the scenarios evaluated for each plant. 

Sulfuric Acid Plant No. 5 

Base Scenario: SA Plant No. 5 has a total vanadium catalyst toad capacity of 0.160 kiloliters (kl) 

catalysh'ton &SO4 day. Current] y, the actual vanadmm catalyst load 1s 0.144 kl catalystiton 

H?S04 day. 

Scenario la: Increase tlte actual capacity of the vanadium cataiyst load from 0.144 to the 

maximum of 0.160 kl cataiyst/ton H2S04 day. This scenario examines the cost of achieving a 

2.8 lblton H~SOJ short-term emission limit on a continuous basis. 

&Scenario 1: This scenako examines the cost of achieving a 3.5 lbiton H2S04 emission rate. For 

SA No. 5, this emissions rate can be achieved on a continuous basis by increasing the actual 

capacity of the vanadium catalyst load up to maximum in beds 1 through 3. and replacing the 

cataiysr in bed 4 with cesium catalyst. 
Scenario 2: This scenario examines the cost of achreving a 2.0 lbiton &SO4 emission rate on a 

continuous basis. This emissions rate could be achieved by adding vanadium up to catalyst 

capacity in beds 1 through 3, repiacing the catalyst in bed 4 with cesium, and reducing the SO2 

gas strength at the converter inlet to 10.5O/0. The reduction of SO2 gas strength at the inlet in 

order to achieve the 2.0 lbiton HzSO~ emission rate will result in a sizeabie production penalty. 

Scenario 3: As an alternative to Scenario 2, Scenario 3 examines another method in which the 

emission rate oi'l.0 lbtton KzS04 can be achieved on a continuous basis. PCS would add 

vanadium up to caialyst capacity in beds 1 through 3, replacing the catalyst in bed 4 with cesium, 

and installing a new converter and superheater. The installation of the new equipment allows the 

facility to avoid reducing the SO? gas strength, while achieving the desired emission rate. 

Sulfuric Acid Plant No. 6 Controll Scenarios 

Base Scenario: SA Plant No. 6 has a totaI vanadium catalyst load capacity of 0.150 hloliters (kli 

catalyst/ton H2S04 day. Currently, the actual vanadium catalyst load is 0.1 50 kl catalyst/ton 

H2S04 day and thus the maximum vanadium is currently used in the plant. 

Scenario 1: This scenario examines the cost of achieving a 3.888 lb/ton emission rate. 

For SA No. 6, this emission rate can be achieved on a continuous basis by replacing the catalyst 

in bed 4 with cesium catalyst. MECS also included replacing a fraction of the existing vanadium 

catalyst in each pass for this scenario. It should be noted that MECS has only guaranteed an 

emission rate of 4.0 Ib/ton; however, this scenario has assumed a 1 tan emission reduction (3.888 

Ib/tonj in order to show some reduction for the purpose of calculating a cost effectiveness value. 

.)scenario 2: Ths scenario axarnines the cost of achieving a 2.0 lblton H2S04 emission rate on a 

continuous basis. This emission rate could be achieved by replacing the catalyst in bed 4 with 

cesium. and reducing the SO2 gas strength at the converter inlet to 10.50/b. The reduction of SO. 

gas strength at the inlet will result in a sizeable production penaity. 

Scenario 3: As an alternative to Scenario 2, Scenario 3 examines another method in which the 

emission rate of 2.0 lbiton can be achieved on a continuous basis. PCS would replace the 

catalyst in bed 4 with cesium and install a new converter. The installation of the new equipment 

allows the facility to avoid reducing the SO? gas strength, whIe achieving the desired emission 

rate. 

A summary of the SA Plant KO. 5 and No. 6 operating parameters and associated scenarios arc 

presented in Table I. 

Capital Recovery Factor 

In performing the cost evaluation for each of the scenarios, there are two types of annual 

operating expenses, indirect costs and direct costs. The direct costs include cataiyst costs, 

screening costs. and catalyst disposal costs. Indirect expenses include adnlinistrative, 

depreciation for equipment, and SO2 recovery credit. The depreciation is calculated through the 

use of a capital recovery factor. The EP-4 Cost Control Manual states the following in regards to 

the capital recovery factor: 

"Anabats use the interest rate to estimate the time vuiue ofnzonejs. It can he thought of as 

a return on investment or the cost ofborrowing. Tile interest rate employed in this 

A,fununl diflers~jkom that used in nor?-governmenral.jirzanriai anulyses. 11 represenn a 
Reasonalle Progress Analysis 

social interesi rate established by the Office of Management and Budget (0MB)jor the 

comparison of public policy issues. 

OMB sets the social interest rarejbr governmental ana&ses and it is currenth set ai 

seven percent. 

However, the social rate of interest is not appropriate for industry. Whet7 choosing 

between alternative air pollution control devices, the industrial planner musf not.onlj> 

take into consideration the costs of each device, the?> musr also understand how the cost 

of each device fits into the financial structure of their business. Furthermore, a nzmmber 

of air regulations allow sources ofpollurion to petitioiz.for exrensions on deadlines, 

var.iances~from the regulation, or exemptionjkom installing control dmices, based upon 

the economic impact that equipment would have upon the source. In these cases, the 

sowee majjJind it useful PO apply their own interest rate to the calculation of control 

costs. Common itzievest rates used by indust? and accepted by the EPA .for source 

petitions include the business' current borrowing rate, the current prime rate, and other 

acceptable industpial rates of return. " 

For the reasons stated above. the application of a 7% interest rate is not appropriate for this 

analysis. Furthermore, the EPA Cost Conrrol Manual does not require the use of 7%. A 15% 

rate is being used to account for the project costs as well as for the lost capital available for 

funding other projects that could have positive return on investment at the facility. This rate is 

appropriate because the return on investment target for projects at the Aurora facility is 15%. 

Calcuilation of Annual Emission Reductions and Cost Effectiveness 

In performing the cost effectiveness, the total annualized cost is divided by the estimated annual 

emission reductions associated with each scenario. The emission reductions are based the 

percent reduction from the maximum 3-hour emission rate in 2009 (IbJton) to the target emission 

rate (Ib/ton) for each scenario times the maximum annual emission rate in past ten years 

(tonsiyr). The use of the baseline actual production data to establish an emissions baseline for 

cost effectiveness calculations is in accordance with a recent EPA determination. See 74 Fed. 

Reg. at 44,321 (Aug. 28, 2009). In connection with EPA's review of the cost effectiveness 

analyses for the Salt River Project ("SRP") Navajo Generating Station in Anzona, EPA found 

that SRP's use of "the same 24-hour average actual emission rate from the highest emitting day 

used for its modeling inputs7' used for BART modeling was incorrect. Id. EPA revised SRP's 

calculations accordingly "by starting with baseline emission rates for NOx averaged over 2004- 

2006 . . . ." Id. EPA's determination in the SRP context is in line with the agency's requirement 

that baseline emissions "represent a realistic depiction of anticipated annual emissions for the 

source." 70 Fed. Reg. at 39,167 (July 6.2005). Using actual baseline emissions instead of the 

BART modeling baseline leads to a more accurate-and higher--cost effectiveness estimate for 

control options being evaluated. As pointed out by EPA, using the BART modeiing baseline to 

calculate cost effectiveness overestimates actual emissions and does not provide a realistic 

estimate of anticipated annual emissions from each source. h this evaluation, the maximum 

production rate during the PSD actual baseline period for each unit is used to perform the cost 

effectiveness evaluation. The maximum production rare during the baseline period is multiplied 

by the percent reduction from the maximum 3-hour emission rate in 2009 (Iblton) to the target 

emission rate (Ib!ton). 
Reasonable Pmoress 8naMsis 

Cost Effectiveness Evaluation Results 

The following presents the details of the cost effectiveness evaluation for SA Plants No. 5 and 

No. 6. Table 2 presents the basis for the cost evaiuatjon and cost effectiveness for each the 

scenarios. 

Sulfuric Acid Plant No. 5 

For Scenario la, there would be a one-time direct cost of $237,720 for maximizing vanadium 

catalyst to capacity in beds 1 through 4. This would allow the plant to continuously achieve a 

short-term emission rate of 3.8 Ib SOz/ton &SO4 or a 5 tordyear emisston reduction. The cost 

per ton of SO: rernoval will be $26,4X4/ton. Thts value is not considered cost effective. Table 3 

presenrs the detailed calculations for Scenario la. 

For Scenario 1, there would be a one-time direct cost of $2,024,45 1 for S,4 Plant No. 5 including 

the cost of additional vanadium in beds I through 3, the total costs of replacing bed 4 with 

cesium, additional screening costs, and used catalyst disposal. This wouId allow the plant to 

continuously achieve a short-term emission rate of 3.5 lb SOdton H2SOs or 165 tonsiyear 

emission reduction. The cost per ton of SOz removal will be $3,456/ton. This value is not 

considered cost effective. Table 4 presents the detailed calculations for Scenario 1. 

For Scenario 2, there would be a one-time direct cost of $2,034,451 for SA Plant No. 5 including 

the cost of additional vanadium in beds 1 through 3> the total costs of replacing bed 4 with 

cesium? additional screening costs, and used catalyst disposal. This scenario will also include 

recurring direct annual costs from a production penalty resulting in $9,778,087 of lost product. 

This would alow the plant to continuously achieve a short-term emission rate of2.0 Ib SOz/ton 

H2SOd or 962 tonsiyear emisst on reduction. The cost per ton of SO2 removal will be $1 O,67Yton. 

This value is not considered cost effective. Table 5 presents the detailed calculations for Scenario 

7 -. 

For Scenario 3, there would be a one-time direct cost of $16,543,000 for SA Plant No. 5 

inciuding the cost of additional vanadium in beds 1 through 3. the total costs of replacing bed 4 

with cesium, additional screening costs, and used catalyst disposal, a new convener, and a new 

superheater. Furthermore, since the installation of the new converter and superheater would 

require approximately 10 months for completion, there would be a production loss at the facility 

due to reduced steam generation from the sulfuric acid plant and a cost for lost cogeneration. 

The one-time production and cogeneration penalty would be approximately $45,276.986. This 

would allow the plant to continuously achieve a short-term emission rate of 2.0 lb S02/ton 

H2S04 or 962 tondyear emission reduction. Thus, the cost per ton of SOZ removal will be 

$13,65l/ton. Tls value is not considered cost effective. Table 6 presents the detailed 

calculations for Scenario 3. 

The following tabie summarizes the cost effectiveness analyses for each of the SA Plants No. 5 

scenarios described above. 
Reasonable Progress: Anahis 

- 

b. The emission reductions are based tihe percent reduction fiom the miximum 3-hour emission rate in 2009 (lbtton) 

to the target ernmion rate (Ib/ton) for each scenario times the maximum annual emssion rate in past ten years 

itonsly-) 

c. Based on the total annual~zed costs divided by the annual emission reduction. 

- - 

! 1 

Scenario l a: Maxrmmg vanadium catalyst. 

Scenano 1: Maximize vanadium catatyst and replace pass 4 with cesium cataiyst, 

Scenano 2: Maximize vanadium catalyst. repiace pass 3 with ceslum catalyst. and reduce SO2 gas strength at the 

inlet of the converter from 11 .% to 10.5'3'0. 

Scenario 3: Maximize vanadrum catalyst. replace pass 4 with cesium catalyst. repiace existing converrer with a new 

48 ft diameter converter. and replace No. 1 superheater to obrain optimwn temperature In Pas 2 

I 

Sulfuric Acid Plant No. 6 

I 

For Scenario 1, there would be a one-time direct cost of $1 ,go?,% 1 for SA Plant Yo. 6 including 

the cost of additional vanadium in beds 1 through 3? the total costs of replacing bed 4 with 

cesium, additional screening costs, and used catalyst disposal. This would allow the plant to 

continuously achieve a short-term emission rate of 3.888 lb SOliton H2S04. It should be noted 

that MECS has only guaranteed an emission rate of 4.0 lb!ton; however. this scenario has 

assumed a 3.888 Ib/ton (1 .O toniyr reduction) in order to show some reduction for the purpose of 

calcuIating a cost effectiveness value. Thus, the cost per ton of SO- removal will be 

$452,59Wton. This value is not considered cost effective. Table 7 presents he detailed 

calculations for Scenario I. 

For Scenario 3, there would be a one-time direct cost of $1,907,93 1 for SA Plant No. 6 inciuding 

the cost of additional vanadium in beds 1 through 3? the total costs of replacing bed 4 with 

cesium, additional screening costs, and used catalyst disposal. This scenario will also include 

recurring direct annual costs from a production penalty resulting in $13.232.609 of iosl product. 

This would allow the plaut to continuously achieve a short-rem emission rate of 2.0 Ib SOz/ton 

H2SOd or 1.1 1 1 tons~year emission reduction. Tne cost per ton of SO. removal will be 

$11,4i 4hon. This value is not considered cost effective. Table 8 presents the detailed 

calculations for Scenano 2. 

I 

For Scenario 3. there would be a one-time direct cost of $14,125.000 for SA Plant Eo. 6 

including the cost of additional vanadium in beds 1 through 3, the total costs of replacing bed 4 

with cesium, additional screening costs? and used catalyst disposal, a new converter. and a new 

superheater. Furthermore. since the installation of the new converter would require 

approximately 10 months for completion. there would be a production loss at the facility due to 

reduced steam generation fiom the sulfuric acid plant and cost for lost cogeneration, The one2-10 

Sulfuric Acid Annual Emission 

Ptnnt No. 5 Target 1 Annual Emission Capital Investment Total Annualized Costs Cost EfCectiseness 

Scenario I (lb SOZhn Add) * Reduction (ton~vr) b. ($1 6S/_vri (Siton) ', 

I 

I I j 1 

I r~ 1 a 3 8 I 

! >.5 165 $2.03.45 I $5 ~9.490 $3.456 

I 1 2.0 I 962 1 $2.024.45 1 I 10266.4XL [ 51 0,672 

1 1 2.0 1 96'1 ) $1b.543.000 1 S !3.1?2.11 7 I 13.65: I a. Based on h4ECS SO- ernisslon hit euaranree on a conrinuous basis. 
SH!TI@W'PWO Reasonable Progres Anafysis 

time production and cogeneration penalty would be approxrrnateiy $53,687,154. This would 

aliow the plant to continuousiy achieve a short-term emission rate of 2.0 lb SO2/ton H.SO.4 or 

1,111 tons/year emission reduction. Thus, the cost per ton of SOz removal will be $13.816/ton. 

Thls value is not considered cost effective. Table 9 presents the detailed calcuiations for 

Scenario 3. 

The foIlowing table summarizes the cost effectiveness analyses for each of the SA Plants So. 6 

scenarios described above. 

a. Based on MECS SO2 emission limn ,pirantee on a continuous basis 

b The emlsslon reducfions are based the percent reductmn from the maximum 3-hour emission rate m 1009 (lblton) 

to the rarget emission rate (Ibitoni for each scenarlo lmes the maxlmum annual ermsslon rare In past ren years 

(tons yr) 

. c Based on the total annuaiized costs dlv~ded by tile annul emissron reauct~on. 

Scenano 1 Replace pass 4 with ceslum catalyst and replace incremental amount of vanadlum catalyx 

Scenano 2 Replace pass 4 wlth cesium catalyst, and reduce SO: gas strength at the inlet of the converter from 

! 1 5O.o to 10 550 

Scenano 3 Replace pass w~th ceslum catafyst and replace exlsting converter with a new 48 fi dlarneter converter 

2.2.3 Conclusion 

URS performed a detailed control technology evaluation following the RP evaluation guidance 

in 40 CFR Part 51. Appendix Y. Under various scenarios for SA Plant KO. 5 and No. 6, the cost 

per ton of compound removed under all of the evaluated scenarios is higher than those that 

would be considered cost effective. Therefore, the evaluatioi~ concludes that further emission 

reductions for SA Plants No, 5 and No. 6 are not cost effective and not reasonable for the 

purpose of Regional Haze reduction goals and confirms the conclusions contained in the NC 

Reglonal Haze SIP dated December 17, 2007. Since no cost effective control measures were 

identified, the remaimng three statutory factors were not evaluated in this report. 
Tables 


TABLE 3 

SCENARIO Ia - COST ANALYSIS FOR 3.8 LBRON HZS04 - SULFURJC ACID PLAiiT NO. 5 

MAXIMUM VASADIUM CATALYST 

PCS PHOSPHATE COMPANY 

URS PROJECT YO. 31827076 

Basis: lj MECS Inc. 

2) MECS -Cesium and vanadium catalyst cost. 

CPCSPholphate ~n~rnetlnngndin-^ , ,pressurt: 

Dtrect Costs Max 

Vanadium BasislCommene, 

Cos! of ies~urn Catalyst Replacerntnr Cost (Bed 4 crslum, SO 

Addinonal catalyst (9 43 kl catalyst ttmw cost of 

Cost of Addrtiond Vanadrum Caraiyst (Bed 1.1.3.4j $237.720 vanadium (94.00!1 I 

Addmonal screening cost $0 

Us& catalyst dispo~i con (9 0 1 XILI %n 

Total Capital Cost $237.720 

Dirert Aauual costs 

Elccrnclt): 15" increased pressure drop $0.05 iKwi 

Indirect Annual Coats 

kdmtnis~nt~oa 

Prom Taxes 

Insulilnc~ 

hp~tal Reco\ery (Cwum Catalyst) 

Capmi Rwovrry (Vanadlun~ Catalyst 6 

Additional acreentag and D~sposol i 

Credir for ac~d recoverv 

Total Annual Cost 

Maximum baselme actual cmlssion rase 

Lrnpmvcd Conrrol Eficrenc) Over Baselrnt 

CostAon oTSOI removai 

34.754 2% TCC: van Nuswnd Rcmhoid 

$2.377 1% TCC van Nostrand Rernhoid 

$2.377 I?," TCC van Nostrand Reinhold 

60 (1590 rare ot mum and 10 vr equipment litel 

Si7.366 (!5% rate of return and 10 yr qurpment lrli') 

($383) lncrea~ed sulEur ii~oxtde conventon I@ S47/to!i acid 

2.025 tpy (based on rnaxtrnm nnnuai etn~aslons) 
T.4BLE 4 

SCENARlO 1 - COST ANALYSIS FOR 3.5 LB/TON H2S04 - SULFURIC ACID PLAh'T NO. 5 

CESIUM CATALYST IN 4TH PASS 

PCS PHOSPHATE COMPANP' 

URS PROJECT NO. 31827076 

P_ - -. Basis: I\ MECS Sns. 

2) MECS- Cesium and vanadium catalyst cost 

Direct Cost$ 

Cost of Cesrum Catalyst Replacelnenr Cost (Bed 4 ;esrum i 

Catalvst. Remove. Ke~nstail and Saees 

C$taiysr Frerght 

Ciuaiu 

Total Capital Cosl 

Direcr AnnuaI cosm 

Eteccncirv (5" rncreaseti pressure drop $0 05 ,Xw i 

Annual produciion loss due w reduced SU: Suer& at convener inie? ilons P,O,I\TJ 

Cosi of annual prcnJuLtinn ioss dur ro reduced SO: Sl~~ngh at conwrter inlet 

Indirect Annual Costs 

Adm~nism~on 

Propeny lax& 

Insurmct 

Capml Recovery ( Ces~urn Catalyst, 

Caprtal Recoven, (Vanadturn Catalyst B 

Add~ucnai screening and Dlsposaii 

Credl: for acid rwovm 

hlaximum baaelme actual em1salon rare 

Improved Conlroi Ffficimcv Owr Baseline 

Cesium 

Catalyst 

Retrofit 

Total of wrsiysr mad of t 81.2 ki csralys~ tines cost of 

piacing vanadlm wtth cesium ($8 00n) 

Addnional caialvs? ijq 33 kl catalm itrnes wsr of 

\anadrum (94.00~11 

MGCS 

MECS 

MECS 

$40 489 2% TCC urn goswnd Kernhold 

$20.245 I % TCC van Koswnd Urlnhold 

$20.24: IS, TCC vat1 Nostrand bmhold 

$288.836 1 IS?+ raw of rrlwn md 10 y: equipment lifcj 

$1 04.3 15 (1 5% mie of rerum and I0 yr equipmcnl life1 

(%I I.8581 increued sulfur droxidc convemon (3 $4711011 ard 

8.1 YO ((based 3 i ih SO;!!on acrdt 

Costhn of SO, removul 
TABLE S 

SCENARIO 2 - COST ANALYSIS FOR 2.0 LBITON H2S04 - SULFURIC ACID PLANT 30.5 

CESlCM CATALYST IN 4TH PASS AND REDUCE SO2 GAS STRENGTH TO CONlrERTER 

PCS PHOSPHATE COMPANY 

URS PROJECT NO. 31827076 

e 

Basis: 11 MECS he. 

2) MECS - Cesium and vanadium cstalyst cost. 

Direct Costs 

Cost of Ccsrum Catalyst Repiacmicnt Cost (Bed 4 cesium) 

Cost of Addlaonai Vanad~urrr Cntaivsl (Bed 1.3.31 

Ca!alvst, Remove, Re~nsull and Screcn 

Cablyst Frergh~ 

Quart. 

Total Capital Cost 

Direct Ann~nl costs 

Eiccmcxy (5" ~ncrwscd pressure drop 50.05 Kw i 

Annuai production loss duc to reduced SO2 Strength at convener inie~ (tons P,Og).ri 

Cost of annual product~on loss duc to reduced SO2 Skrcngth at convcncr inld 

Isdirect .4nnual Costs 

Admin~strauon 

Properiy Faxes 

insurance 

Cnpiwl Recovcry iCes1um Catalyst) 

Cap~tal Recovery iVanadru~n Catalyst & 

Additlolial sc~ue~l~ng anti D~sposiilj 

Crcdit for prlc recnvnv 

lmproved Control Eflicmcy Uvcr baselme 

Emisslori Reduction 

Costiton ol'SO-, removal 

Ces~urn 

Catalyst 

Retrefrt 

Totai of cntaIy8t load of 181.2 k! calalysT tlmcs cost of 

rcolacing vanadium with cenum (58.W11) 

Addibonal catalyst 159.43 kl catalp? tunes cost oT 

vmaaun (%4.00;% 

MECS 

EPA-450'3-85-0 13 

(acfm- 2 10,660) 

Reducrng SO? gas srrcngth from 11. to 10.58,3b results In 

40 TPD pmriucnon penalty umes 358 davs pcr vear 

(9890 ut~lmlion) 

Hiwed mi average gros rnarpn of S2Ol;ron PIC;, 

r.roduced~soiJ 

2% TCC vnn Nosnand Ranhold 

) % TCC ran Nosvend Reinhold 

I? b TCC var, Nusnnd Rcrnhoki 

(1 5% rate of return nud 10 yr cquipmenl hie) 

(15% me olrcturn and 10 yr cqulpment iifc) 

rp) I based on manmum annual emisszons I 
TABLE 6 

SCENARJO 3 -COST ANALYSZS FOR 1.0 LEITON H2S04 - SULFURIC ACID PLANT NO. 5 

CESIUM CATALYST IR lTH PASS AHD ADDITIONAL EQUlPiMENT CAPITAL 

PCS PHOSPHATE COMPANY 

Ulds PROJECT NO. 31827076 

2i MECS - Caium and vaaadiom cn:alvst mat 

3) Eruting cooveier is rcpiaced with a new 48 11 diameter msvener and pan 4 i. rrpi~fed with SCX-Z(WO cstltvst. No. 1 Superhester ir rrplaced to obtain 

Cost of Ccsburn Caraipsr Rcphcmnrl Cost ftlM 4 ccsburn! 

Cesium 

Cntalyst Basis:Commenrs 

Krtrufit 

Tnul ofcalsly~ ioad of 22s 2 ki iati!yt tmes iost of 

SI.S'.5,6(K, repiacmg vanadrum w~th ccsiurn (S8 00111 

Calalyi, Rcmovc. Rcnmali and Sacos $285.813 MECS 

Ncw C'onvurler S10.575.783 MECS 

ioral New Equcomcnr J13.6.3j57S3 MKS 

Tc~ral Capttnl Casr 516,543,OMl 

mrccr Annual mklr 

SjI(O.Xh(l ?",. TCC van Nusmlki Rcinhoiil 

klG,+l?O 1% TCC'van Nmmnd Rcmho!d 

1 165.430 1':. TCC van Nw~mui Rcinirold 

S.X.755 t 15':. rare ofretun and Ill yr wulpmem hfcj 

Maxtrnum badrnc actual muaslun mre 2.025 rpy fbascd on maxunum anoual Lmlsrlunsj 
TABLE 7 

SCENARIO 'i -COST ANALYSIS FOR 3.89 LBtTOX H2S04 - SULFURIC ACID PLAKT NO. 6 

CESIUM CATALYST IS 4TW PASS 

PCS PHOSPHATE COMP-tNY 

URS PROJECT YO. 31827076 

- 

Bask 1) MECS lnr. 

21 MECS - L'wunl and vanadium catalyst cost. 

Direct Cctsts 

Cocr of.4ddmonal Vanadium Cawivst iaed i.2.3) 

Cataiyxr, Remove, Remnuall and Screen 

Catalyst Freigni 

C)uLm 

Total Capitat Cost 

Direct Annual cow 

Electricity 1 '" increased pressure drop 40 05 ~Ku) 

Annunl producnon loss due to reduced SO-, Strcngtlr st converter inlei iloos f20,:yri 

Cost of annual pmd~tion loss due lo rcouced SO, Strength at umvmer mlet 

lndirecr Aonuol Cwls 

Cap~tal Recovery (Vanadium Catnlysr & 

Add~t~ondl screeuvlg and Dlspo.;tIi 

Credl: tor ac~d recover). 

Total Annual Cov 

Lmpn~ed Control Efficlmcy Over Basetlnc 

Cesium 

Catalyst 

Retrofit 

Total of catalyst load of Ih8 3 kl cataiys tmes coat o! 

repiac~ng vn~dlwn w~th ceslum ($8 c)O/l) 

Add~ttonai catalyst - 60 04 ki t~mer, cosi of aanadlum 

catalyst ($1 0O:it 

MECS 

MECS 

MECS 

2% TCC van Nosrrand Remhold 

I80 TCC van Kosrmnd Re~uhold 

I"/" TCC van Nosirand Re~nhold 

(15% raw of re:m and :(I yr yurpment iiki 

11 5% rate of ream al~d 10 )T cqumpmcnt hiej 

Increased suhr dtoriLir canverswn I:$ f47;ron actd 

tpy (based on maximum annwl emlss1onL) 
TABLE 8 

SCENARIO 2 - COST ANALYSIS FOR 2.0 LBfrON H2S04 - SULFURK ACID PLANT YO. 6 

CESlLrM CATALYST IN 4TH PASS AND REDUCE SO2 GAS STRENGTH TO CONVERTER 

PCS PHOSPHATE COMPANY 

URS PROJECT NO. 31827076 

- - 

Basts: 1) MECS lnc. 

21 Haldor Topsw. Lnc. - Cesium and vnnadium catalyst cost. 

pirect Costs 

Cost of Cestum Catziyst Replamrncnf Cat (Bcd 4 ceslrirn i 

Cosr of Additional Vanadium Catalyst (l3cd 1.2.3) 

Caulyst. Removc, Rcinatall and Scrcon 

Catalyst Fretgl~t 

Qwm 

Total Capital Cost 

Dirwt Annual costs 

Elccmc~rs (5" lncrcaacd pressurc hop $0.05 ,F;iv! 

Annuai product~on loss due !o reduced 50, Sucngth at umvcner tnle: (tuns P,O&rl 

Cost o<annuai productton iuss due u) rtauced SO: Strcngtii at cunvcrtcr inlet 

Indirect Annual Costs 

Admintstrat~on 

Prupeny Tams 

insurar~ce 

Capnai Rccove~y ((lcsium Cataiystl 

Capttak Remvcr)i Waitad~uni Cataiyst & 

Addmonai screening and D~spusai~ 

Crcdit for ad rccovm 

Total Annual Cost 

Maxtmum bascilne WNal emission rdlc 

CosWion of SO? removal 

Cesium 

Catafyst 

Retrofit 

Total uf catalyst load of 168.3 ki mraiysr times cost or 

repimng vnnad~un~ with Lesum (S8.Wfi) 

Addltronai catalyst - biJ.09 ii: tjmcs cost of ana ad run^ 

caiolyst tS4.OO!I) 

MECS 

MECS 

MCS 

EPb.45013-85-0 12. 

tach= 11 0.660) 

Reducing SO, gas strength &om 1 ! .5 to 10.5% rcsults in 

500 n'D prductroo penally ilrnes 358 days per year 

(98% utrIir.auon) 

Based on avuagc yoss margin oFSZOl/;on P20, 

protiuccd~sold 

240 TCC vw Noshilnd RetnhoId 

1% TCC van NoswndRe~nhold 

I% TCC van Nosnand Remhoid 

15% ratc of return 2nd 10 yr equprncnt Ifd 

ii5% ratc olrcnim and 10 yr cqurpmcnt Itk: 

in~~cuscd sulfur dlox~de mnvcrsioti i:n; Fj71tori ad 

tpy (bas& on maximum altnual emtssrons) 

k (baser! 2.0 ib SOyron ac~d) 

lpy (baed on 2.0 Ib SD,/mn ac~dl 
TABLE 9 

SCENARIO 3 -COST ANALYSIS FOR 2.0 LBrrON HZSO4 -SULFURIC ACID PLANT NO. 6 

CESIUM CATALYST IN 4TH PASS AND ADDITIONAL EQUIPMENT CAPITAL 

PCS PHOSPHATE COMPANY 

URS PROJECT NO. 31827076 

Basis: I) MECS Inc 

2) iisldor Zopscre. Inc - Cerium and vanadium ntnlysr con 

JfEriahnpnccd with a new 48 ft diameter converter f 

Cesium 

Calaiyst 

Retrofit 

Toel orcalalyst ioad of248.1 kl wtnlvst ltmus cost of 

r~qlacmg vanadturn with crsturn (58 M):l) 

Addruonal catalvst - 181 ki llmcs cuut oiv~tdlurn 

Caldlyst (41M)iil 

MECS 

MECS 

MECS 

,MECS 

Cost of Cesatm Catalyst Replacanent Cost (Bed 4 cmrwnl 

Cost of Aditrronal Vanamum Catalyn (Red 11,3) 

SetaiysL Remove. Retnstatl md .keen 

New Convcmr 

Ncw Supehcnlcr 

lolal Capitsl Cost 

Aununi productrun lors duc ui 10 month dcwnttrne lo udd new cqulpmenl Irons f'2i)5iyr~ 

huai producrtvn luss dw io rcdilccd SO Slrcngth at convcrrw rnlct lrona \O.:yrt 

Cwt of UNZM~ producriun loss due to reduck SO SIC~~L$I at convrrtcr ltilcl 

~aaal Costs 

Ahtn~wmon 

Propcny Taxer 

losurdnw 

Caprrdl Kccovcrv (Cesium Caldysll 

2% TCC van Nostrand Remhoid 

I% TCC ran Nuahond RnnLold 

I"% TCC van "lostrand Rutniioid 

115% rate olrctum and I0 yr eqmprnml I& 

Capital Rccovcry (Vannd~um Catalvsi 

addthonai sncentng aird Utspowl. rlew 

converter ad sepcrhca%cr, and one lllnc 

prudilcr~un loss and cogennntlm loss) 

C~drl tor aid re~~vcq 

(15% rate airam and 10 pr rqutpment hie) 

increased aulfur d~oxidc cmvmmn 157 Sii7:lon acid 

'futal Annual Cml 

ipy ibdicd on nuximum annual cmw~om] 

Improved Conrrol Effic~ncy Cvcr Bascitne 
APPEMDM A 

MECS DESl6tl AND COST IHFQRMBTII11 
Catalyst Designs for PCS Aurora 

Dastgcs are based on 3 year turnarounds 

I PLANT 5 I PLANT 6 I 

Scenario 1: What is the lowest $02 Won em15sion rate that can be continuously achieved on a 3hour average basis, 

without lowering the 502 gas strength (i.e. production penal%y) and significant capital? 

Pass 4 is replaced wlth SCX-2000 catalyst for both plants 

SO2 rant 11 5% 

Pbnt Rate 3400 STPD 

SO2 Erntss~ons 3 5 lbllon 

Temperature (deg F! 

Bed Type Volume (Ll inle: Outiel 

1 XLP-220 117.800 794 1156 

2 XLP-110 123.400 907 1025 

3 XLP-!I0 155,000 845 911 

4 SCX-2000 18:,200 734 787 

TOTAL 577,400 

(170 LJT) 

SO2 conc 11 5% 

Plant Rate 3700 STPO 

SO2 Emlsswns 4 0 bfion 

Temperature (deg Fi 

Bed Type Volume (Li inlet Outlet 

1 XLP-220 130.000 785 112d 

2 XLP-$10 122,100 8il 937 

3 XLP-ll0 14E.30 833 910 

4 SCX-2O[M 168.300 734 790 

TOTAL 568.900 

(154 UT) 

Scenario 2: In order to achieve a 2.0 fbfton emlsslon rate continuously on a f-hour average basis, what would be the 

SO2 gas strength and associated productlon penalty, without slgnififant capital? 

Pass 4 is repieced with SCX-2000 catatysi for both plants. 

so2 COW 10 5% 

Planl Rate 3000 STPD 

SO2 Emrsslons 2 0 lblton 

Bed Type Vdume (L) Inlet Outkt 

1 XLP-220 117.8CC 794 1"1? 

2 XLP-110 123.4IM 907 1011 

3 XLP-110 155.000 &15 896 

4 SCX-2MIO IS1.2W 734 769 

TOTAL 577,400 

SO2 Conc '0 5% 

Plant Rate 3200 STPD 

SC2 Emswans 2 0 bitor 

Temoerature ldeo Fi 

Bed Type Voiume <:'I lnlel Outiet 

I XLP-220 130.M1G 783 1141 

2 XLP-110 122 100 811 932 

3 XLP-110 148500 833 871 

4 SCX-ZOOC 168 300 734 763 

TOTAL 568 900 

Scenario 3. In order to achieves 2.0 lblton erniss~on rats continuously on a 3-hour average basis, what modifications 

would be required and what would the capital cost6 be lo achieve the emission level? 

PIant 5 exWng conveter is replacad with a new 46 f! 

diameter wnverter and paas 4 is replaced with 

SCX-ZOO0 cataiyst. No. 1 Superheater IS replaced to 

&tam optimum temperature In pass 2. 

SO2 Conc 11 5% 

Plant Rate 3400 STPD 

SO2 Ernrss~ons 2 0 IbAon 

Ternperatwe (deg F) 

Bed Type Vdurne (1: Me? Out!et 

1 XLP-220 322.600 734 1156 

2 XLP-110 :56.6@2 824' 975 

3 XP-110 201,000 845 887 

4 SCX-ZOOC 228,200 734 775 

TOTAL 708.4OC 

(206 UT) 

Plant 6 emsting conveter is replaced with a new 48 ft 

diameter converter and pass 4 is replaced with 

SCX-ZOO0 catalvst. 

so2 Ccnc 11 5% 

Plant Rate 3700 STPD 

SO2 Ernrsslans 2 0 IbIIon 

Temoerabre idea Fi 

6ed Type Volume {L: lniet 0uiet 

1 XLP-220 133.400 783 1131 

2 XLP-110 170,600 811 971 

? XLP-110 216,60@ 833 @-32 

4 SCX-2OW248.200 734 773 

TOTAL 770.800 

(208 LJr) 

Nore that new Superheater IS reoulrsd 
Client: PC§ 

Description: Catalyst Options 

Location: Aurora, NC 

Scenario I: 

Plant 5 

Catalyst, Remove, Reinstall and Screen * 

includes New SCX-2000 and Make-up XLP 

Plant 6 

Catalyst. Remove. Reinstall and Screen * 

lnciudes New SCX-ZOO0 and Make-up XLP 

Scenario 2: 

Plant 5 

Catalyst, Remove, Reinstall and Screen ' 

Includes New SCX-2000 and Make-up XLP 

Plant 6 

Catalyst, Remove, Reinstall and Screen * 

includes New SCX-2000 and Make-up XLP 

Scenario 3: 

Plant 5 

New Converter incl Catalyst Replacement 

New Superheater 

Plant 6 

New Converter incl Catalyst Replacement 

Rev: 0 

Project #: 

By: SGK 

Date: 25-Jun-18 

Estimate Type: +/- 25% 

" Screening includes all beds. 

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