Spring Summer 2016

Tenke Fungurume looks to the future with second acid plant Page 7

T O D A Y

Sulfuric Acidwww.H2S04Today.com Spring/Summer 2016

C o v e r i n g B e s t P r a C t i C e s f o r t h e i n d u s t r yKeystone Publishing

P.O. Box 3502

Covington, LA

70434

Address Service

Requested

PRST STD

U.S. PSTG

PAID

GPI

IN THIS ISSUE > > > > global acid market: changing fundamentals page 10

fiber bed mist eliminator refresher: theoretical fundamentals vs. real world page 17

Quick fit pre-assembled acid-proof lined equipment page 34

Tenke Fungurume looks to the future with second acid plant Page 7

T O D A Y

Sulfuric Acidwww.H2S04Today.com Spring/Summer 2016

C o v e r i n g B e s t P r a C t i C e s f o r t h e i n d u s t r y

Keystone Publishing

P.O. Box 3502

Covington, LA

70434

Address Service

Requested

PRST STD

U.S. PSTG

PAID

GPI

IN THIS ISSUE > > > > global acid market: changing fundamentals page 10

fiber bed mist eliminator refresher: theoretical fundamentals vs. real world page 17

Quick fit pre-assembled acid-proof lined equipment page 34

Vol. 22 No. 1 Covering Best Practices for the Industry Spring/Summer 2016

Dear Friends, Welcome to the Spring/Summer 2016 issue of Sulfuric Acid Today magazine. We have dedicated ourselves to covering the latest products and technology for those in the industry,

and hope you find this issue both helpful and informative. As we send this issue to press, were gearing up for another information sharing event, our 2016 Australasia Sulfuric Acid Workshop, April 4-7 in Townsville, Queensland, Australia. This version of the workshop is packed full of informative presentations from worldwide industry professionals. Some of the key topics for this years meeting include converter maintenance, catalyst screening, sulfur handling and filtration,

heat exchanger maintenance and materials, mist elimination solutions, acid resistant linings and materials, process gas

monitoring, materials of construction for equipment and hydrogen safety and incident reviews. If you would like more information about the event, please visit www.acidworkshop.com. Meanwhile, we hope this issue of Sulfuric Acid Today will provide you with some innovative technologies for your profession. Be sure to read such articles as Global acid market: changing fundamentals, (page 10), Solutions for common problems in sulfur spraying (page 12), Dry and wet precipitatorsthe yin/yang of off-gas acid production (page 14), Fiber bed mist eliminator refresher: theoretical fundamentals vs. real world (page 17), Aggressive corrosion and demanding conditions need aggressive solutions (page 20), Modernization of a

sulfuric acid plant in three easy steps, (page 21), Acid mist elimination in sulfuric acid plants (page 24), Weir Minerals Lewis Pumps manufactures API 610 11th edition qualified pumps as standard (page 26), Creating reliable, durable seals in glass-lined steel equipment (page 30), Quick Fit pre-assembled acid-proof lined equipment (page 34) and Moisture-free surface cleaning technology: NitroLance (page 36). I would like to welcome our new and returning Sulfuric Acid Today advertisers, including Acid Piping Technology Inc., Beltran Technologies, Central Maintenance & Welding, Chemetics Inc., Clark Solutions, Conco Services Corp., Corrosion Service, Dresser-Rand, El Dorado Metals Inc., Haldor Topse A/S, Koch Knight LLC, KSB AMRI Inc., OPSIS, MECS Inc., NORAM Engineering & Constructors, Optimus, Powell Fabrication & Manufacturing, Saint-Gobain NorPro, Southwest Refractory of Texas, Spraying Systems Co., Southern Environmental Inc., STEULER-KCH GmbH, VIP International, Weir Minerals Lewis Pumps and W.L. Gore & Associates. We are currently compiling information for our Fall/Winter 2016 issue. If you have any suggestions for articles or other information you would like included, please feel free to contact me via e-mail at [email protected]. I look forward to hearing from you.

Sincerely,Kathy Hayward

froM the PuBLisher

on the Cover 7 the tenke fungurume

mine in the democratic republic of Congo brings its second sulfuric acid plant on line.

dePartMents4 industry insights news items about the

sulfuric acid and related industries

28 in the news

32 Lessons Learned Case histories from the sulfuric

acid industry

38 faces & Places Covering sulfuric acid industry

events

40 Calendar of events

10 global acid market: changing fundamentals

12 Solutions for common problems in sulfur spraying

14 Dry and wet precipitatorsthe yin/yang of off-gas acid production

17 Fiber bed mist eliminator refresher: theoretical fundamentals vs. real world

20 aggressive corrosion and demanding conditions need aggressive solutions

21 Modernization of a sulfuric acid plant in three easy steps

24 acid mist elimination in sulfuric acid plants

26 Weir Minerals Lewis pumps manufactures apI 610 11th edition qualified

pumps as standard

30 Creating reliable, durable seals in glass-lined steel equipment

34 Quick Fit pre-assembled acid-proof lined equipment

36 Moisture-free surface cleaning technology: NitroLance

36 Info sharing at CRUs conference, Sulphur 2015

PUBLISHED BYKeystone Publishing L.L.C.

PUBLISHERKathy Hayward

EDITORApril Kabbash

EDITORApril Smith

MARkETIng ASSISTAnTConnor Chapman

DESIgn & LAYOUT

281-545-8053

Mailing Address: P.O. Box 3502Covington, LA 70434

Phone: (985) 893-8692 Fax: (985) 893-8693

E-Mail: [email protected]

SUBSCRIPTIOnSU.S. Plant Personnel -Complimentary

U.S. Subscription - $39 per year (2 issues)Internatl Subscription -$59 per year (2 issues)

Subscribe Online: www.h2so4today.com

features & guest CoLuMns

20

34

21

Sulfuric AcidT O D A Y

INdUSTry INSIgHTS

Moroccos King Mohammed vi inaugurates oCP projectsJORF LASFAR, MoroccoEarly this year, Moroccos King Mohammed VI in-augurated a fertilizer plant and the first stage of a seawater desalination plant for an overall budget of $600 million USD. The new plant, Africa Fertilizer Com-plex, is dedicated to supplying the Afri-can market. Initiated by Moroccos Office Cheri-fien de Phosphate (OCP), these large-scale projects represent the Sovereigns new commitment to south-south coopera-tion and the willingness to support OCP innovation and sustainable development initiatives. The move also represents a consolidation of Moroccos leadership in the global phosphates market. Africa Fertilizer Complex, which was developed upon the instructions of King Mohammed IV, aims to accompany the growth of African markets through continued and regular supply of fertiliz-ers (DAP/MAP/NPK). The new plant consists of a sulfuric acid plant (1.4 million tons per year), a phosphoric acid plant (450,000 tons per year), a fertilizer plant (one million tons of DAP per year), a 62-megawatt solar station and up to 200,000 tons of fertil-izer storage infrastructure. This mega project encourages tech-nological and environmental innovation in sulfuric acid production through a 10 MW electric energy gain and an impor-tant reduction in seawater consumption. Sulfur dioxide emissions are significant-ly lower than international norms. The seawater desalination plant, part of OCPs water strategy, aims to meet the additional needs created by the develop-ment of a Khouribga-Jorf Lasfar platform without additional demand for conven-tional water. The plant, which will be built in three stages, will reach an annual produc-tion of 75 million cubic meters. For more information, please visit www.ocpgroup.ma.

Boliden invests in new acid plant at harjavalta smelterBOLIDEN, SwedenBoliden Harjavalta operates two acid plants that produce sul-furic acid and liquid sulfur dioxide from smelter off-gases formed in the copper and nickel smelting processes. Boliden is investing in a new and more efficient acid plant using best available technology. The investment program, that will run from 2016-2019, consists of two parts. The first part will be about 65 million EUR with the total investment estimated to be 90 million EUR.

The performance of Boliden Har-javalta has developed positively over sev-eral years. This investment improves our technical infrastructure, which is fun-damental for our long term competitive position. Continuity of the site, together with the improved environmental perfor-mance, is important for our local commu-nity too, said Timo Rautalahti, general manager, Boliden Harjavalta. With the new plant in operation, the efficiency and environmental perfor-mance of Boliden Harjavalta will improve in several areas. SO2 emissions will be re-duced by 20-25 percent and cooling water by 40 percent, as heat is recovered, result-ing in higher energy efficiency. In addi-tion, minor bottlenecks will be resolved, especially on the copper line, making fu-ture expansion projects possible on both the copper and nickel lines. For more information, see www.bo-liden.com.

iffCos Paradeep unit receives accolades ODISHA, IndiaThe Indian Farmers Fer-tilizer Co Operative (IFFCO), a multi-unit cooperative with 40,000 member coopera-tives and over 50 million members, is one of the biggest agricultural cooperatives in the world, generating over $5 billion in turnover. It supplies fertilizer and services to agricultural producers and currently holds five fertilizer manufacturing units in India, including one at Paradeep. IFFCO Paradeeps achievements have recently been recognized through various awards in the fields of CSR, energy sav-ings, technical innovation, water conserva-tion, and environment management. These awards include: FAI Environment Protec-tion Award 2015, Greentech Environment Award 2015, Kalinga Safety Award 2014, CII 16th National Award of excellence in energy management 2015, Paradip Port Trust for handling the highest tonnage raw materials in 2015 and Krushak Bandhu Award 2012. The Paradeep unit was taken over by IFFCO in October 2005. The unit consists of two sulfuric acid plants with a capacity of 3,500 MTPD per plant, a phosphoric acid plant having a capac-ity of 2650 MTPD of P2O5 (the worlds largest single stream) and three DAP/NPK fertilizer plants with a capacity of 19.20 lakh metric tons per annum. The principal raw materials are rock phos-phate, sulfur, sulfuric acid and ammonia which IFFCO Paradeep imports from various countries. The facility also in-cludes a captive jetty located at Paradeep Port as well as unloaders with capacities of 1200 MTPH and 800 MTPH. The raw materials are transported from the jetty to the plant through 5-km long conveyor belts and pipelines. Water required for the plant is supplied from Taladanda Canal 2

WASTEHEATRECOVERYBOILERS

SUPERHEATERSECONOMIZERS

50yearsofmanufacturingexperience 99%lifemeonmedeliveryperformance 20yearsexperienceinSulfuricAcidwasteheatrecoveryequipment

Opmusdelivereditsrstsulfuricacidplantwasteheatrecoverysystemin1996.Acrossthepowerandprocessindustries,weveproducedmoreheatrecoveryboilers,HRSGs,superheaters,andeconomizersthananyacvecompanyintheUSA.OpmusanditsChanuteManufacturingplanthavealongstandingreputaon for highqualityworkmanship and onme performance. Customers trustouruniquemanufacturingexperseandhavecondenceinourqualitycontrolandcomprehensiveprojectexecuon.

Ph:9184919191www.opmustulsa.com

Email:[email protected]

page 4 Sulfuric Acid Today Spring/Summer 2016

De

pa

rtm

en

t

km away from the plant site. Electricity requirements are met through two dedi-cated power plants, each having capacity of 55M, as well as two 110-MTPH coal fired boilers used to balance power and steam requirements. IFFCOs Paradeep unit gives prime importance to the welfare of both its em-ployees and the local population, as well as preserving the environment. For more information, please visit www.iffco.in.

uganda phosphate project beneficiary of China-africa partnershipKAMPALA, UgandaThe construction of Ugandas Sukulu phosphate factory in the Tororo District received a boost of $240 million at the China-Africa Invest-ment and Financing Forum held in South Africa last December. The Industrial and Commercial Bank of China (ICBC) in cooperation with the Standard Bank of South Africa will dis-burse the money in tranches to the proj-ects developer, Guangzhou DongSong Energy Group Company Ltd. The Sukulu facility will consist of a mine and a beneficiation plant with an-nual capacity of two million metric tons, a phosphate fertilizer plant with annual production of 300,000 metric tons, a sul-furic acid plant with annual production of 400,000 metric tons, a 12MW waste heat-based power generation plant and a steel mill with annual production of 300,000 metric tons. The company is expected to hire more than 1,200 local people in all of its plants, in addition to investing in schools, hospi-tals and other public welfare projects. The project will boost agriculture production through the provision of fertil-izers, support infrastructure development through iron and steel production, offer jobs to the region, support other industries and boost our export earnings through value addition of the primary commodi-ties, the Energy Ministrys Permanent Secretary, Fred Kabagambe-Kaliisa, said. The Uganda government has granted mining rights to the investor in the form of a 21-year mining lease, and other ex-ploration licenses to finalize additional exploration work. The government has further provided 600 acres of land to fa-cilitate the development of the industrial complex, the construction of staff resi-dences and the administration block.

new acid plant at indias largest steel producerORISSA, IndiaA new sulfuric acid unit with a capacity of 125 metric tons per day was inaugurated at the Rourkela Steel

Plant (RSP) in Orissa in February. The Rourkela plant, owned by Steel Author-ity of India Ltd. (SAIL), replaced an older, obsolete unit. The acid produced in this unit is used in the companys Coal Chemical Depart-ment, Cold Rolling Mill and Captive Pow-er Plant-I. The surplus production will be marketed externally. RSP has developed 20 new special-ized products, including products for the defense sector as part of its drive to slash the countrys import burden and adopt the Make in India mission. RSP is the first integrated steel plant in the public sector in India. After imple-menting a massive modernization and expansion that is in the last leg of comple-tion, RSP has enhanced its capacity to 4.5 million metric tons of hot metal and 4.2 million metric tons of crude steel. SAIL, Indias largest steel producing company, is among the seven Maharatnas of the countrys Central Public Sector En-terprises. SAIL has five integrated steel plants, three special plants, and one sub-sidiary in different parts of the country. For more information on SAIL, please visit www.sail.co.in.

Jordan and Chinas firms to build $1.3 billion fertilizer plantAMMAN, JordanThe national Jorda-nian Phosphate Mines Company and Chi-nas Chongqing Minmetal and Machinery Import and Export Co. (CMMC) signed an agreement in the first quarter of 2016 to build a $1.3 billion industrial fertilizer complex in the southern city of Aqaba. Officials in Amman hope the new project will breathe life into the strug-gling company and the fertilizers pro-duced will be exported to several markets across the world. Thousands of jobs will also be created from the project, helping to absorb numbers of unemployed among the rapidly growing population. Jordan Phosphate Mines Co., found-ed in 1949, is a mining and fertilizer pro-ducer operating in the Hashemite King-dom of Jordan, which has the fifth largest phosphate reserve in the world. The com-pany is the second largest exporter, and sixth largest producer of phosphate, with production capacity exceeding 7 million tons of phosphate annually. CMMC, founded in 1983, specializes in contracting overseas projects, exporting labor services, self-supporting and acting as an agent for the import and export of various commodities and technologies, and engaging in domestic trade. For more information on Jordan Phosphate Mines Co., please visit www.jpmc.com.jo. For more information on CMMC, please visit www.cqmmc.com. q

INdUSTry INSIgHTS

Sulfuric Acid Today Spring/Summer 2016 page 5

De

pa

rtm

en

t

T he Democratic Republic of Congo (DRC), deep in the heart of Africa, is home to some of the worlds largest known copper deposits. Tenke Fungurume Mining (TFM), located in the Lualaba Province, is one of the countrys largest copper producers, as well as the worlds premier producer of cobalt. The facility, which includes surface mining, leaching and SX/EW operations, currently produces 205,000 metric tons of copper and 16,000 metric tons of cobalt each year. As capacities increase, so do the demands for sulfuric acid, an important component in processing the ore. After the successful installation of the sites first sulfuric acid

plant in 2009, increasing capacities led to higher demands for acid. Always looking ahead, the company quickly realized the benefits of adding a second, larger acid plant, which came online in the first quarter of 2016. This addition brings the companys investment in the area to over $3 billion so far, representing one of the largest private investments in the countrys history.

history The Tenke Fungurume deposits are located within concessions totaling over approximately 600 square miles in the Lualaba Province of the DRC, about 110 miles northwest of Lubumbashi,

the republics second-largest city. In the southeastern section of the country, the area was first explored in 1917 by Union Miniere, a Belgian mining company that was later succeeded by La Generale des Carrieres et des Mines (Gecamines), with drilling beginning in 1919. The Mobutu government nationalized the project in 1969. A private/government consortium, Societe Miniere du Tenke Fungurume, then made an investment of $280 million. In 1996, TF Holdings Ltd. (TFH), a subsidiary of Lundin Group, acquired majority interest in the project through a public tender process. Tenke Fungurume Mining was formed for the purpose of

developing the deposits of copper, cobalt and associated minerals. Today, Freeport-McMoRan Inc. owns 56 percent of Tenke Fungurume Mining; Lundin Mining Corp holds 24 percent; and Gecamines, which is wholly owned by the government of the Democratic Republic of Congo, owns 20 percent. The Tenke Fungurume deposits are sediment-hosted copper and cobalt deposits with oxide, mixed oxide-sulfide and sulfide mineralization. The dominant oxide minerals are malachite, pseudo malachite and heterogenite. Important sulfide minerals consist of bornite, carrolite, chalcocite and chalcopyrite.

Tenke Fungurume looks to the future with second acid plant

By: April Kabbash, Editor, Sulfuric Acid Today


Co

ve

r S

to

ry

Aggregate reserves total 99 million metric tons (mt) of ore at 3.19 percent copper and .37 percent cobalt with recoverable metal amounting to 7.2 billion pounds of copper and .9 billion pounds of cobalt. adding acid The next logical step in streamlining production at TFM was the addition of on-site sulfuric acid manufacturing. The facilitys first acid plant, AP1, was brought on-line in 2009 with a capacity of 600 metric tons per day. Before that, TFM was importing all of its acid from other locations. The original acid plant met some, but not all, of the facilitys needs, even after a de-bottlenecking of AP1 in 2012, which increased annual acid production name plate capacity to 825 metric tons per day. While this was an improvement, it still didnt provide all the acid necessary for the facility. TFMs acid requirements are constantly increasing with the mining of ores with higher copper content, said Daudet Zeka Songesa, acid plant superintendent at Tenke Fungurume. Producing acid at the site to meet this increased demand is more economical than purchasing and transporting sulfuric acid to the site, with an improvement in acid availability. As an additional benefit of this project, the number of acid trucks on the road will be reduced, improving the safety and environmental impact risks in the region. So, planning began for a second, larger acid plant. After the successful integration and operation of AP1, there was no need to reinvent the wheel when planning AP2. We built on our success with the first acid plant, creating the second on a larger scale, said John Wellington, Tenke Fungurumes acid plant manager. A formal and systematic lessons learned session was conducted during the feasibility study phase of AP2. Key project team members met to review all aspects of the design and generate ideas on what could be done to make AP2 better than AP1. While AP1 was a very successful project, improvements can always be made, said Wellington. Several beneficial changes came out of the sessions, including changes to the plant layout to incorporate recommendations from the operators and an upgrade in the DCS system with an improved interface.

Layout changes included increasing the size of platforms around the front end of the sulfur furnace, in the area where sulfur guns are changed, to allow for better access. The DCS interface upgrade helped simplify things, while still providing all the vital information. The DCS screens were revamped to enable operators to see the core of the acid plant in only two screens, said Chemetics Sales Manager for Sulfuric

Acid, Herbert Lee. This means it is easier to keep track of all the critical operating parameters at a quick glance. One new feature for AP2 is a continuously operating caustic scrubber that increases recovery of SO2, reducing emissions to less than 20 ppm. AP2 will also include a power cogeneration plant, with a nameplate capacity of 20 MW, which is expected to come online in

March. The power produced will be used to reduce the overall power demand from the grid and greatly improve reliability. Chemetics, with their depth of knowl-edge and cutting edge technology, was brought on board in the early days of the project. As with AP1, Chemetics provided the core detail engineering for the acid plant and supplied key proprietary equip-ment. Our project team focused on leverag-ing proven experience from the first acid plant project and developing new innova-tions to improve reliability and capital costs for the second plant, which has twice the capacity. said Songesa. The Chemetics-patented, all-stainless converter featured a modularized design, instead of the conventional field erection approach. The converter was shipped to the site in prefabricated modules after be-ing trial fit in the shop, significantly reduc-ing cost and improving the overall qual-ity of the fabrication. Site assembly was significantly simplified using a small crew compared to the traditional field erec-tion, said Lee. The final quality of the converter is also better as most of the weld-ing is done in a controlled shop environ-ment. An internal steam superheater and inter-reheat exchanger are located inside the core of the converter to eliminate hot gas ducting between beds 1 and 2 and beds 2 and 3. The acid towers, acid distributors, and strong acid piping incorporated proven Chemetics Saramet sulfuric acid alloy. To minimize welding on site and avoid the associated quality risk the acid tow-ers were supplied to site completely shop fabricated. The acid distributors feature complete modular bolted assembly and the Saramet acid piping was supplied in pre-fabricated spools suitable for shipment to site in standard shipping containers, fur-ther minimizing installation costs and op-timizing schedule. The newest generation of ISO-FLUX trough distributors was installed in the acid towers to minimize packing chips fouling while reducing the total number of parts, simplifying installa-tion and maintenance. The sulfur furnace was also completely prefabricated before being shipped to the site. Chemetics design features individual combustion air control to each sulfur gun for optimal air-sulfur mixing. This design also requires no internal baffle walls. Chemetics also played vital roles in commissioning and start-up training services throughout the project. TFM currently employs approximately 3,400 people, a number that is not expected to change with the new plant. We are not planning to hire any additional people to operate the acid plant, said Wellington, but rather be more productive at the current manpower level. Ninety-eight percent of TFMs employees are DRC

The Tenke Fungurume facility will produce all the sulfuric acid it needs onsite, with the addition of ap2.

This schematic of the ap2 converter shows the inter-reheat exchanger.

as with ap1, Saramet alloy acid towers were prefabricated, trucked in and lifted into position.

In the ISO-FLUX trough distributor, acid flows from the main header to the bottom of the trough. It then flows up via a series of calming plates which also filter out debris. Choking of flow orifices through the downcomers is virtually eliminated.

The prefabrication of the acid towers saved the TFM team time and money.


Co

ve

r S

to

ry

citizens, making the company one of the largest employers in the region.

on the fast track The quick time frame of the project, along with the location, presented a unique set of obstacles for the team. The fast-paced project, which at $245 million came in below the original budget, took approximately 24 months from feasibility to start up. Commissioning of AP2 was very successful due to a combination of an adaptable and flexible commissioning team made up of FMI, TFM, Chemetics and Hatch employees as well as the robust proven design of AP2 that allowed the TFM operators to easily transition to the new plant. First acid was made in early February and the plant had already exceeded nameplate capacity of 1,400 metric tons per day within less than three weeks. This was a fast-tracked project that involved coordina-tion of project personnel from several different companies,

including Freeport-McMoRan, TFM, Chemetics and Hatch, who were located in very different time zones, said Songesa. We had to find ways around that, to avoid slowing down the process. Several members of the Freeport-McMoRan project team were moved to South Africa to reduce inefficiencies associated with extreme geographical and time zone differences, as well as to ensure purchasing, logistics and shipping issues could be dealt with quickly. Having them closer to the site avoided lag time and helped move the process along. All key project team members also attended frequent design review meetings to ensure all parties were on the same page. Transportation of equipment within the DRC was another challenge. Ground transportation in the DRC has always been tricky. The terrain and climate of the Congo Basin present serious barriers to road and rail construction, making shipping of large, heavy equipment very difficult. These difficulties were overcome by ordering long-

lead equipment quickly and optimizing equipment design to fit within the shipping limitation, taking advantage of modular pieces whenever possible.

dedicated to environmental, community improvements At Tenke Fungurume, safe production is the most important factor in the companys success, and everyone shares responsibility for safety, both in and out of the mine. TFM is committed to managing the mine in a way that benefits the local community, promotes good governance, respects local culture, minimizes disruption to the ecosystem and supports the evolution of the country toward sound mineral development, said Songesa. The company has also made significant investments in community development ranging from education and agriculture to healthcare and infrastructure development. Since 2006, TFM has funded a total of $120.4 million in community development projects. Additionally, since the commencement of commercial production, TFM has set aside 0.3 percent of net metal sales revenue to fund the TFM Social Community Fund. Since the commencement of production, contributions committed to the fund have totaled $23.6 million. Both TFMs direct community

development and TFM Social Community Fund projects are focused on supporting sustainable development of the concession communities by investing primarily in education, healthcare, infrastructure and agriculture. TFM was the proud recipient of two significant awards at the 2015 iPAD DRC Mining & Infrastructure conference in Kinshasa, winning recognition as both Mining Company of the Year and Best Performer in Environmental Management. These just highlight the ongoing commitment the company has made, both to its employees and the region.

Looking to the future While Tenke is currently producing more copper and cobalt than ever before and serves as a major employer and

support for the entire region, the company refuses to simply rest on its laurels. The addition of the facilitys second sulfuric acid plant should help it reach new heights in the coming years, while also cutting costs. Production of acid from AP2 allows processing of higher acid-consuming ore, and it is anticipated to provide an improvement to copper and cobalt production due to the certainty of acid supply at an improved operating cost compared to importing acid, said Wellington. In addition, TFM continues to engage in exploration activities and metallurgical testing to evaluate the potential of the highly prospective minerals district at Tenke Fungurume. According to Songesa, These analyses are being incorporated in future plans for potential expansions of production capacity, which could exceed 1 billion pounds of copper per year. q

The Chemetics-designed sulfur furnace was built offsite. The furnace provides optimal air-sulfur mixing with no internal baffle walls.

ap2s stainless steel converter was assembled from prefabricated modules, simplifying installation.

Tenke Fungurume is one of the largest copper producers in the Democratic Republic of Congo, producing 205,000 metric tons per year.Team members celebrate the first acid production from the new plant.


Co

ve

r S

to

ry

As the first quarter of 2016 com-menced, low commodity prices continued to overhang global markets. The most sig-nificant impact on the traded sulfuric acid market is lower consumption to support base metals leaching, which has resulted in significant demand destruction in markets such as Chile and the United States. Meanwhile, low crude prices continue to overhang the market, but by-product sul-fur production has remained stable because of healthy refinery operating rates. Around 90 percent of sulfur is used to produce sulfuric acid and of the acid produced, around 50 percent is used to support phos-phate fertilizer production. It is used as a raw material to process phosphate rock to produce phosphoric acid, a key intermedi-ate in products such as diammonium phos-phate (DAP). Last fall, signs of weakness in the phosphate fertilizer sector were be-ginning to emerge and sulfur prices began to respond accordingly. With limited de-mand for phosphate fertilizer products in key import markets such as India and Latin America, phosphate producers began to push for lower sulfur prices, particularly in China, the largest consumer of sulfur

on a global basis. In North America, the major domestic benchmark sulfur price, the Tampa quarterly price, settled at a $15/long ton reduction for the first quarter at $95/long ton delivered. In the first half of February, the outlook turned increasingly bearish and major phosphate producer Mosaicthe largest consumer of sulfur in North Americaannounced it would cur-tail phosphate production by up to 400,000 metric tons in the first quarter in response to weaker market conditions. At the time of writing, this and other signals in the global market were leading to speculation of fur-ther downward pressure in sulfur prices. A turnaround in the phosphate fertilizer mar-ket as the year progresses could see sulfur prices firm, however. If sulfur prices remain under down-ward pressure, there are implications for the sulfuric acid market. It is already fac-ing challenging market conditions for 2016, mainly because of the aforementioned re-duction in demand to support metal leach-ing. The dip in sulfur prices impacts buyer sentiment and, if prices slide significantly, has the ability to impact levels of sulfur-based production versus purchasing of in-

cremental sulfuric acid from the market. This is occurring at a time when pro-duction of sulfuric acid traded in the global market is stable, so any further pressure to place volume would be challenging. Pro-duction is stable because despite the bear-ish tone in the base metals market, it has had more of an impact on consumption of sulfuric acid for leaching rather than smelting operations. Smelters are said to be running as close to capacity as possible in order to achieve lower overall unit produc-tion costs amid a weak mining sector. This results in stable production of by-product sulfuric acid, which drives global trade and sets prices. In Chile, the worlds largest importer of offshore sulfuric acid, weaker demand for sulfuric acid for copper leaching has resulted in significantly reduced import requirements. As a result, smelter acid producers in Japan and South Korea (his-torically key suppliers to Chile) have been forced to look for alternative markets to keep product moving. This hasnt been an easy task, with most smelter acid moving at negative netback prices at the time of writ-ing. Increased demand in markets such as Vietnam and Thailand has provided some relief, but as the year progresses, the PAS-AR smelter in the Philippines is expected to increase production levels as capacity is expanded, resulting in the need to market additional tonnage. Therefore, demand in southeast Asia will be key in keeping the region balanced. China will play a role in absorbing supply, but this could result in curtailing of sulfur-based acid production if acid prices move low enough, thereby ex-acerbating conditions in the sulfur market if further demand destruction is realized. Looking ahead, Chiles import needs could see a rebound if conditions in the copper sector improve, but a retreat to historical levels is not expected given a longstanding forecast for declining import needs. The decline is being driven by lower overall consumption requirements in addi-tion to increased domestic production. Peru is the largest supplier to Chile, supplying around one million metric tons/year to the country, but its excess sulfuric acid levels could contract if leaching projects in the region progress. The two most likelyTia Maria and Macobrehave the potential to consume up to a combined 800,000 met-ric tons/year of sulfuric acid, reducing its export availability accordingly. This could help Asian suppliers increase export vol-umes to Chile in the long-term. Outside of Asia, Europe is another key exporter of offshore sulfuric acid. The majority of acid is delivered to Mo-

rocco, Brazil and the United States. At the time of writing, European suppliers were comfortable but market participants are closely watching to see if major phosphate producer OCP in Morocco curtails its production as Mosaic in the United States announced. If it does, this is likely to re-sult in lower demand for imported sulfuric acid. Planned smelter maintenance could counterbalance any dip in demand from Morocco, however. Looking to 2017, a shift in European trade could be seen if additional sulfur-based sulfuric acid production by Sher-ritt in Cuba ramps up as planned. Its Moa nickel leach facility is expected to com-mence operations of additional sulfuric acid production in the third quarter 2016. Once running at optimal utilization, this could back out up to 400,000 metric tons/year of offshore acid imports. This acid is currently supplied mainly from Europe, so similarly to how suppliers in Asia are cur-rently dealing with lower demand in Chile, European suppliers will be forced to look to alternative markets to place product. Some market players are making stra-tegic moves to deal with a shift in trade-flows. For example, sulfuric acid producer and trader Glencore, which has smelter production capacity globally including in Asia and Europe, is investing in additional import ability in the United States. It is understood new tanks will be operational in Savannah, Ga., by the end of 2016. This will represent Glencores second import lo-cation in the United States following tanks going into service in Houston, Texas in the fourth quarter 2014. The import abil-ity gives Glencore options for managing its global sulfuric acid portfolio amid shifting market fundamentals. In summary, the key factors to watch for the remainder of 2016 are the perfor-mance of the phosphate fertilizer sector and the subsequent impact on the sulfur and sulfuric acid markets. The health of the base metals sector is also important, both in terms of a rebound in demand for leach-ing and production of smelter acid. Further ahead, changing fundamentals including a shift in tradeflows in Asia, Europe and Chile/Peru will influence the performance of the global sulfuric acid market. Acuity Commodities provides insight into the sulfur and sulfuric acid markets through price assessments, data and sup-porting analysis. The newly-formed com-pany is currently offering North American-focused services, but will be adding global content as the year progresses. Please visit www.acuitycommodities.com for detailed information. q

global acid market: changing fundamentalsmarkET oUTlook

By: Fiona Boyd, Director, Acuity Commodities

Developed by Corrosion Service more than 60 years ago, Anotection is the original anodic protection corrosion prevention solution for sulfuric acid equipment. Whether your project is new build, rehabilitation or routine maintenance, our talented team of engineers and technicians are empowered to understand the unique characteristics of every inquiry and provide a solution that is tailored to you.

Prevent corrosion and reduce iron contamination.Anodic protection solutions for:

Sulfuric Acid Storage Tanks Sulfuric Acid Coolers Sulfuric Acid Piping

[email protected]

ANOTECTION SERVICE IS AT OUR CORE


Fe

atu

re

Problem #1: achieving proper atomization Solution: Understand drop size The reason atomization is so important in sulfur burning is that it has a direct impact on the rate of heat transfer between the combustion gas and the sulfur. Spray nozzles used on sulfur guns are often selected based on flow rate. A better approach is to select spray nozzles based on drop size and performance. Heres why: A single droplet with a

diameter of 500 microns has roughly the same volume as 121 droplets with diameters of 100 microns.

However, the surface areacoverage of the smaller droplets is approximately 484 percent larger.

This increased surface areaincreases the rate of heat transfer.

The smaller dropletsdecrease the likelihood of sulfur impingement on furnace walls and baffles and the chance of sulfur carryover.

Optimizing sulfur spraying is dependent on many variables including atomization, drop size, residence time, gun placement and operating conditions in the furnace. Computational Fluid Dynamics (CFD) modeling is a powerful tool that can determine the optimal drop size for full evaporation and complete vaporization prior to installation to minimize production disruptions. In addition to ensuring proper atomization will be achieved, CFD can also determine the best placement for the guns to avoid sulfur wall contact and carryover to downstream equipment.

Problem #2: Maintaining consistent spray performance Solutions: Use nozzles with a high turndown ratio or consid-er air atomizing nozzles Another common problem challenging sulfur producers is maintaining consistent perfor-

mance over a wide operating range. Spray performance needs to be consistent during start-up, low flow operation and peak flow operation. Pressure is changed to obtain different flow rates. However, when pressure is changed, spray performance changes as well. For example, when using hydraulic nozzles, a decrease in pressure results in an increase in drop size and contraction of the spray pattern and coverage, and leads to incomplete evaporation or vaporization. There are a few options for solving this problem:

Use nozzles with a highturndown ratio.

Use multiple sulfur gunsand control flow rate by turning guns on or off and/or adjusting the operating pressure of the individual nozzles on the guns.

Consider changing fromhydraulic to air atomizing nozzles. While pressure adjustments still affect performance, the changes are more subtle. This is because the atomizing air pressure can be adjusted along with the feed pressure in order to help

maintain more consistent performance across a wider range of flow rates.

Refer to the four images in Fig. 2. The upper left image shows a BA WhirlJet hydraulic nozzle spraying at 5 gpm (19 lpm) and the upper right shows a FloMax air atomizing nozzle spraying at 5 gpm (19 lpm) which represents normal operating conditions. As production decreases, there is a need to decrease the flow rate in the furnace which is sometimes accomplished by lowering pressure. The image on the lower left shows the same BA hydraulic nozzle lowered to spraying 2 gpm

(8 lpm) to reduce the flow rate. Note the streaky spray pattern, condensed coverage and larger droplets at the lower pressure as compared to the upper picture. When comparing the two photos of the FloMax air atomizing nozzles, the change is more subtle and no visual difference can be detected. The performance is more consistent even at the lower flow rate and pressure.

Problem #3: Plugged nozzles Solutions: Evaluate air atomizing nozzles, hydraulic nozzles with clean-out ports and/or purge with steam or air Plugged nozzles are another frequent and disruptive problem, not unique to sulfur spraying. Whenever there is a set orifice size, there is potential for some-thing to build up or lodge within that orifice. Installing properly sized strainers upstream of the nozzle is important and can often eliminate plugging. Plugging can also be caused by contaminants, such as carsul, in the sulfur, or molten sulfur may solidify inside the nozzle when operating at lower flow rates or when sulfur guns are removed. The solidification is caused by the loss of velocity that is present when operating at higher pressures. Possible remedies to these plugging problems are to use a sulfur gun that has a clean-out port, or purge with steam or air. Another approach is to use air-atomizing nozzles. The atomizing air pressure continu-ally moves any low flow sulfur through the gun and minimizes plugging. Simply using hydraulic nozzles with larger orifices can result in performance problems as larger orifices require less pressure drop. The outcome is larger droplets and turndown is limited. For more information on optimizing sulfur spraying, visit www.spray.com or contact your local Spraying Systems Co. representative. In the U.S. and Canada, call (800) 95-SPRAY. In other regions, call (630) 665-5000. q

Fig. 2: The difference between hydraulic nozzles and air-atomizing nozzles under different levels of pressure is easy to see.

Fig. 1: CFD model shows the difference in wall impingement when using hydraulic nozzles (top) and air atomizing nozzles (bottom).

Solutions for common problems in sulfur spraying


Fe

atu

re

World-class Technologyfor Worldwide Markets

We deliver a wide range of products and services, from engineering studies through to full EPC projects for the Sulphuric Acid Industry

Products & Services:

Chemetics Inc.(headquarters)Suite 200 2930 Virtual WayVancouver, BC, Canada, V5M 0A5Tel: +1.604.734.1200 Fax: +1.604.734.0340email: [email protected]

Chemetics Inc.(fabrication facility)2001 Clements RoadPickering, ON, Canada, L1W 4C2Tel: +1.905.619.5200 Fax: +1.905.619.5345email: [email protected]

Chemetics Inc., a Jacobs companywww.jacobs.com/chemetics

Acid Plants Sulphur Burning Metallurgical Spent Acid Regeneration Acid Purification & Concentration Wet Gas

Proprietary Equipment Converter Gas-Gas Exchanger Acid Tower (brick lined and alloy) Acid Cooler Furnace SARAMET piping & acid distributor Venturi Scrubber

Technical Services Turnaround inspection Operations troubleshooting Process optimization Feasibility studies CFD (Fluent) analysis FEA (Ansys) study

In non-ferrous metals plants, materials such as molybdenum, copper, zinc and lead are separated from the ore through a roasting or smelting process. The ore contains sulfur impurities along with other components. The sulfur is used downstream to manufacture concentrated sulfuric acid. For example, in a molybdenum roaster application, the molybdenum sulfide (MOS2) ore is converted to MOO3. During this conversion, the sulfur is liberated through the off-gas in the form of SO2 and SO3 along with other solid particulate. The SO2 is used to produce concentrated sulfuric acid after the off-gas is cleaned and made SO2 rich. In order to make the off-gas SO2 rich it is passed through a series of pollution control and process equipment, referred to as the gas cleaning system. The gas cleaning system removes solid particulate, SO3 and moisture. The off-gas exiting from the gas cleaning system is sent to a sulfuric acid production plant. The gas cleaning system typically consists of the equipment shown in Fig 1. Each component of this gas cleaning system has a specific purpose in order to make the off-gas SO2 rich. All of the components have to function in harmony to ensure maximum removal efficiency. The spray cooler cools the off-gas to approximately 600 degrees F. The cyclone and the dry electrostatic precipitator (dry ESP) are used to capture solid particulate and recover raw material, which is usually recycled back to the roaster for further recovery. The saturator and the gas cooler saturate and sub-cool the off-gas to remove moisture. During this saturation and sub-cooling process, the SO3 vapor is converted to H2SO4 mist. The wet electrostatic precipitator (WESP) captures the H2SO4 mist and the second-stage gas cooler sub-cools the gas further. The off-gas exiting from the second-stage gas cooler is SO2 rich and is sent downstream for sulfuric acid production. It is important to note that the H2SO4 mist is removed from the off-gas, not only to make it SO2 rich, but also to prevent corrosion in the sulfuric acid production plant. As noted in Fig. 1, the dry ESP performance has a significant

impact on the performance of the downstream components. An underperforming dry ESP will mean higher carry-over of solid particulate and otherwise recoverable material to the saturator and WESP. This valuable particulate will now be transferred from the off-gas into the weak acid solution or other liquid, and the recovery of marketable material becomes almost economically impossible. In addition to the loss of marketable material, the H2SO4 mist removal efficiency in the WESP is significantly compromised. Increasing unnecessary solid particulate loading that is carried over from an underperforming dry ESP reduces the effectiveness of the WESP to capture H2SO4, thereby negatively impacting the downstream production of concentrated sulfuric acid. Both dry and wet ESPs work on the same principle whereby solid particulate and H2SO4 mist

are charged and collected under the influence of an electric field. In order to maximize removal efficiency within the boundaries of this equipment, the highest possible values for secondary voltage (kV) and secondary current (mA) are employed. The inlet particulate loading, in the case of the WESP, will be a total of the solid particulate plus H2SO4 mist. This total inlet loading is one of the parameters that dictate the maximum attainable values of secondary voltage and current. A higher particulate loading will directly result in a lower secondary current. Therefore, an underperforming dry ESP could have a severe detrimental impact on the WESPs performance in this application. Fundamentally, the higher the recovery percentages the dry ESP can attain, the better a given WESP will perform downstream in the off gas process. Additionally, given any particular WESP design, it should be noted

that it is a constant efficiency device, therefore increases in unwanted particulate from the dry ESP will cause increases in downstream particulate loading to the sulfuric acid production plant. A reduction in WESP performance is often attributed to design or maintenance problems with the WESP. But frequently, the problem begins upstream at the dry ESP. Whenever a WESP suffers from a sudden and unexpected drop in performance, evaluating a variety of variables including the operational characteristics of the upstream equipment is recommended. The dry ESP electrical characteristics are a good place to start, to ensure the root cause is not upstream of the WESP. When the performance of a WESP is degraded, the solid particulate and H2SO4 mist loading to the downstream acid plant also increases. This increase in loading downstream of the WESP can

cause a variety of maintenance issues ranging from build-up on the process fan blades to corrosion in various areas. The build-up on the fan blades often unbalances the fan, forcing either a reduction in production or worse, complete shut-down. Therefore, it is critical to monitor and maintain the WESP performance on a continuous basis. Since the performance of the WESP is affected by the performance of the upstream gas cleaning components, especially the dry ESP, it is critical to always monitor, evaluate and maintain the gas cleaning equipment as a complete system. Once it has been established that the performance of the dry and wet ESPs are degraded due to aged components or an increase in process flow parameters, a modification to the system will be necessary. There are numerous ways to determine the most economical way to achieve performance improvements. Dry ESP technology has seen many significant technological advancements in the last 30 years. Advancements such as use of high frequency power supplies and wide plate spacing have resulted in relatively small dry ESPs achieving extremely high collection efficiencies. These technology advancements can be economically retrofitted into the existing ESP casing. Some upgrade concepts include performing partial or complete upgrades using pre-fabricated components to reduce process down time and field construction costs. There have also been advancements with regard to materials of construction. The use of fiberglass reinforced plastic (FRP) and polypropylene fabric-type collecting electrodes provides a viable option over lead when replacing or upgrading WESPs. In summary, economical upgrade strategies can be devised in order to ensure continuous and reliable operation of both dry and wet ESPs, but those upgrades need to be evaluated in the context of the whole system rather than individual component evaluation. For more information, please contact Michael Johnson of Southern Environmental, Inc. at (850) 944-4475 or [email protected] or visit www.southernenvironmental.com. q

Fig. 2: Dry eSp (left) and wet eSp (right).

Fig. 1: Typical gas cleaning process.

dry and wet precipitatorsthe yin/yang of off-gas acid production By: Hardik Shah, Applications Engineer, Southern Environmental, Inc.


Fe

atu

re

Sulfuric Acid Catalyst

Unmatched emission reduction

- hit your targetsStronger regulatory requirements for SO2 emissions are

raising the bar for many acid producers. VK-701 LEAP5 catalyst can help meet these demanding targets.

Topsoe specializes in advanced catalyst technologiesand we aim to provide the most cost e cient catalyst solution. This will o er you signifi cant SO2 reductions,

save you energy and give you longer turnaround cycles - we call this optimal performance.

Sign up for news directly from Topsoe

topsoe.com

Scan the code or go to topsoe.com/sulfur

By: Steve Ziebold, Principal Consultant, and Douglas Azwell, Senior Consultant of MECS, Inc. and Evan Uchaker, PHD Research Engineer of DuPont Clean Technologies

This article provides insight on how mist particles are captured in diffusion fiber beds and what is required to assure sustained state-of-the-art fiber bed mist eliminator performance. The first part of this article briefly discusses the theory of mist capture mechanisms, and the second part describes real world design and quality control. There are three main mist collection mechanisms utilized by high efficiency diffusion fiber bed mist eliminators, as illustrated in Fig. 1. They are: Impaction, Interception and Brownian Diffusion.

impaction The inertial impaction mechanism collects a mist particle in a gas stream when it impacts a fiber. A particle has volume and density. The bigger the particle, the more mass it contains. If the gas velocity is fast enough, the mass of the particle moving within the gas will have adequate momentum to cause it to impact a fiber and stick by weak Van der Waals forces rather than continue following the gas streamline around it. The larger the particle diameter, the more momentum it has, and the easier it is for capture by the impaction mechanism. From a theoretical view, it is true that particles can be collected by impaction if momentum, as represented by the Stokes number, overcomes the drag force in a gas stream where no eddies are present down-stream of the collecting fiber. The Stokes number is represented as:

Where dp = mist diameter, p = mist density, V=mistvelocity,g= gas viscosity and df = fiber diameter. Note V is the interstitial velocity, which is the velocity between the fibers that are present within the matrix of the fiber bed, so it must be corrected for the void space of the fiber bed in the fully wetted, steady state condition during operation to accurately calculate the Stokes number. Thus, the Stokes number is difficult to derive because it requires an understanding of how collected mist is distributed on individual fibers within the fiber bed. Further complicating this is that collecting fibers have a nominal fiber size distribution, so the Stokes number will vary as a function of the diameter of the fiber that the incident particle collides with. The gas drag force is represented as:

Where g = gas density, v = speed of the mist particle relative to the gas, CD = gas drag coefficient and A = cross sectional area of

the collecting fiber. As such, the formulas described earlier can give a crude approximation of collection efficiency due to impaction. However, flow streams in a fiber bed are much more complicated than shown in Fig. 1 due to the complexity of the fiber matrix in the actual fiber bed and how coalesced mist is retained and/or migrates within the collecting fibers.

interception The second mist collection mechanism is direct interception. This means the mist particle is intercepted from the gas stream if it cannot squeeze between two fibers (or if it touches the tangent of a fiber as it passes within the barrier layer between the freely moving gas and the fiber surface, sticking to the fiber by means of weak Van der Waals forces). Consider a particle 1.0 micron in diameter that follows a gas streamline passing within 0.5 micron of a fiber. The particle will touch the fiber and be collected by interception. This mechanism is similar

to the action of a mesh filter or sieve.

Brownian diffusion Impaction and interception are the primary collection methods employed by devices that are designed to remove larger mists from a gas stream. In order to remove sub-micron mist particles out of a gas stream, however, a third mist capture mechanism called Brownian Motion or Brownian Diffusion must be utilized. All molecules in a gas stream are in constant, random, thermally induced motion. This molecular motion causes collisions between gas molecules and suspended mist particles. As mist particles are bumped by surrounding molecules of gas, the momentum exchange causes a randomly oriented zigzag effect on mist particle motion. Since these collisions have little energy, this mechanism is effective for only very small particles (typically less than 1 micron) and decreases in intensity as the particle size increases. Therefore, the smaller the particle, the greater its random

motion (also known as particle diffusivity) and the more likely an incident particle will collide with a fiber and stick (collect) by weak Van der Waals forces during transit through the fiber bed. For describing mist capture by diffusion, the modified Stokes-Einstein equation for diffusivity is used:

Where kB = Boltzmann constant, T = temperature, C = Cunningham slip correction factor, g= dynamic gas viscosity, and dp = mist particle diameter The Stokes-Einstein equation is the theoretical diffusivity of a particle and predicts only the intensity of the random motion a particle exhibits. It should not be inferred that this equation predicts mist collection, which would be true if a fiber bed consisted of a single fiber and the flow stream around the fiber were a textbook flow pattern, as shown in Fig. 1. In reality, the flow of process gas through a fiber bed is much more complex and the path the process gas takes through a fiber bed is torturous. (A single fiber bed for some sulfuric applications contains a length of glass fiber equal to the distance between the Earth and the Moon). Additionally, many other factors contribute to determining mist capture, including the amount of collected mist retained within the fiber bed at steady state, mist residence time as it passes through collecting fibers, mist properties, fiber bed uniformity and general fiber bed properties to name a few. Many academia-based fiber bed mist elimination research studies have been performed in an effort to evaluate mist collection using very small scale filters, often in a dry operating state with very low inlet mist levels. These studies often assume homogeneous liquid distribution to simplify the prediction of mist collection when the filter is saturated. In reality, large diffusion fiber beds in sulfuric acid plant service are not homogeneously saturated, which adds another level of complexity in predicting performance. Therefore, technology provider experience, based on development of semi-empirical models supported by rigorous field measurements, is critical to accurate prediction of diffusion fiber bed collection efficiency and operating pressure drop. The MECS sulfuric acid field mist sampling database has over 50 years of field acid mist measurements in support of Brink fiber bed design models.

real world design & quality control Diffusion fiber bed mist eliminators used in sulfuric acid plants are very large compared to, for example, cartridge filters. One of the product attributes that is very important to

Fig 1: Illustration of mist capture mechanisms.

Fiber bed mist eliminator refresher: theoretical fundamentals vs. real world

Fig 2: example of a fiber bed thermographic image.


Fe

atu

re

control is fiber bed packing uniformity (or homogeneity). As a means of obtaining a visual qualitative perspective of homogeneity, MECS developed a thermographic imaging technique in the 1970s. The test is performed by blowing a controlled flow rate of warm air through the fiber bed while using a forward looking infrared radiometer (FLIR) system to detect temperature variations (hot and cold spots) on the downstream side of the fiber bed as a function of position. Thermographs, however, are only a qualitative indication to determining whether there are fiber bed non-uniformities. To be effective, they must be performed at close range to the element surface using a small temperature gradient with high color contrast. Fig. 2 is a thermographic image dem-onstrating a significant hot spot observed on a parallel packed fiber bed at a weak spot in the packing. This is likely where parallel glass fiber rovings happened to line up when the element was hand wrapped. The only sure way to quantify fiber bed uniformity is with velocity profiles using a velometer. A velometer also is shown in the Fig. 2 thermograph image directly measuring actual gas velocity at the hot spot. Complete velometry measurements are often carried out by MECS to allow for continuous improvement of Brink fiber beds as these measurements relate to variance of raw material supplies and fiber bed manufacturing process. With the same parallel wrapped element shown in Fig. 2, a velocity profile was taken along the entire length of the element that crossed the hot spot (Fig. 3). Measurements indicated gas velocities over some areas were very high (3990 fpm, 340 fpm and 370 fpm) compared to the average over the rest of the length of the fiber bed (~ 50+ fpm). High velocity spikes can significantly reduce theoretical capture of mist particles discussed earlier. When this type of element is placed in service, velocity spikes contribute to poor mist eliminator performance in two ways: penetration of submicron mist particles due to reduced contact time with collecting fibers, and formation of re-entrainment (large particle regeneration) due to increased shear of collected mist draining from the downstream exit gas surface of the fiber bed. Another routine quality control mea-

surement is dry element pressure drop tak-en at a controlled gas flow rate, which is a means of determining the fiber bed dry gas flow resistance. This QC measurement is a good quality check to ensure all elements have the same individual gas flows when placed in service, which ensures all elements work equally together. An imbalance in gas flow between elements will result in less than ideal performance. If one looks at the difference between fiber beds manufactured with identical dry gas flow resistance, one that is wrapped with computer controlled placement versus another that is hand packed, the difference is apparent. The hand wound element will contain velocity spikes as described earlier, while a properly packed fiber bed that was manufactured with the computer controlled placement technique will not. Thus, not only is it important to select a fiber bed with matched dry bed flow resistances, it is also important to manufacture the fiber bed with uniform packing density (high homogeneity) to assure best-in-class performance is achieved for protection of downstream equipment. Also, even if angle and parallel wrapped roving fiber beds are made to the same dry bed resistance, this does not result in the same operating pressure drop in process service under identical inlet conditions. MECS developed the angle roving wrapped diffusion fiber bed mist eliminator in the 1970s as part of an extensive research program using sulfuric acid mist. It was discovered that equilibrium retention of collected mist (and steady state saturated operating pressure drop) is reduced by wrapping glass fiber roving at an angle instead of a parallel orientation (relative to the ground or support tubesheet). With less liquid retained in the fiber bed, this resulted in lower operating pressure drop, lower re-entrainment and higher overall collection efficiency of submicron mist. For many applications, even those outside sulfuric acid, angle wrapped roving diffusion fiber beds typically provide up to 20 percent more gas throughput compared to bulk packed fiber beds for the same operating pressure drop and collection efficiency (or equivalent reduction in pressure drop for the same number of elements). This is due to the fact that a fiber bed that is packed with

computer controlled precision with the fiber at an angle is more uniform than a fiber bed that is packed by hand. Additionally, the angle wrapped interlocking roving is a more stable and uniform pack when compared to parallel hand wrapped roving, bulk packed or donut-style fiber beds. Mullins et. al. (Mullins, 2003) clearly demonstrates that fibers oriented at an angle relative to grade show a marked tendency to allow liquid droplets to flow when the mass of the liquid droplets on the fiber allows them to overcome adhesive forces. This paper supports MECSs research and development findings that a fiber bed with angle wrapping operates with lower liquid retention and lower operating pressure drop. Another innovation developed with the angle wrapped diffusion fiber bed is the bi-component fiber bed design, which virtually eliminates particle regeneration (re-entrainment). A drainage layer comprised of proprietary coarse fiber media is oriented downstream of the collecting layer. Even with the most uniform fiber bed mist eliminator, if only collecting fibers are used, liquid films will easily form between fibers among the interstitial spaces. When these films break, droplets can be produced that add to emissions from the fiber bed. More importantly, if these films form on the gas discharge side of the fiber bed, the result will be particle regeneration of some portion of the collected mist back into the gas stream. The result of re-entrainment is normally mist particles a few microns in diameter or larger. The quantity of re-entrainment depends on several parameters,

especially inlet mist loading, bed velocity and exit velocity. MECS bi-component fiber bed offers a means of reducing the amount of re-entrainment by providing a downstream gas-liquid disengagement zone to allow collected liquid to drain away without further interaction with the gas phase. Re-entrainment control is very important to sulfuric acid customers to minimize downstream corrosion of ductwork, to protect catalyst and prevent high stack emissions. Unfortunately, since re-entrainment is difficult to measure, often clients will use fiber beds without a drain layer and realize only years later the effects of downstream equipment corrosion. Additionally, not all re-entrainment control materials are created equal. MECS experimented with many different materials as part of its research and development program in the 1980s to determine the proper orientation, fiber size and density for this material to achieve proper re-entrainment protection. To illustrate the effectiveness of using a bi-component fiber bed design, two portions of a drain layer were removed from a standing research element shown on the left side of Fig. 4. Gas was pushed through the fiber bed from the inside to outside. When a water solution containing a small amount of soap was injected into the inside of the element, bubble formation was observed on the outside of the element coming from the two areas where the drain layer was removed. This illustrates the effectiveness of the drain layer under flow conditions in reducing formation of bubbles

Fig. 5: Brink Xp Mist eliminators.Fig 3: example of a fiber bed velocity profile.

Fig. 4: Demonstration of effective gas/liquid separation using a drainage layer.


Fe

atu

re

and films at the gas discharge surface of a fiber bed and how significant performance improvement can be realized in sulfuric acid plant service using bi-component fiber beds.

recent diffusion fiber bed innovations As a result of MECS continuous improvement through research and development, there have been recent significant advancements in Brink diffusion fiber bed technology with the introduction of the eXTra Performance XP mist eliminator and AutoDrain. Following a decade of research and development along with over 10 years of acid plant experience, MECS now designs and builds the XP for all acid towers (Fig. 5). For typical tower acid mist loadings, the XP offers the lowest pressure drop available in one-to-one match-ups when compared to other elements. Due to its patented uniform collecting fiber arrangement, XP operating pressure drop is up to 50 percent less compared to the original HE style hand packed fiber bed mist eliminator invented by Dr. Joe Brink in the 1950s. Thus, the new XP fiber bed technology can provide sulfuric acid plant installations with significantly lower operating pressure drop or fewer elements compared to conventional designs. Beginning with the original Brink hanging HE style fiber bed mist eliminator, element seal legs have been used since the 1950s. Another recently patented and demonstrated innovation is the Brink AutoDrain for hanging style diffusion fiber bed mist eliminators. A novel arrangement integrated into the bottom of the element allows for collected mist to drain on the upstream gas side of the element, thus eliminating the need for seal legs.

As shown in Fig. 6, seal legs from hanging fiber beds routed to open distribution troughs result in a very congested space making maintenance very difficult. Fig. 7 shows the area under elements that use AutoDrain. It is apparent the working space around the distributor is significantly more open for maintenance. In addition, using AutoDrain saves significant expense by eliminating element seal legs, plant downtime, and labor required for seal leg installation.

Wrap-up Providing outstanding diffusion fiber bed mist eliminators is not as simple as just using a theory-driven approach to design. In addition to theory, it is important to use field experience in actual sulfuric acid service to provide a product that will consistently meet or exceed industry needs. Since 1958, MECS, Inc., has been the pioneer in development, and improvement of successful Brink Mist Eliminators. Along the way, MECS has improved semi-empirical design models upon which its invention is based. Beyond theory, in order to attain predictable, reliable performance, it is important to assure raw materials are always within specification and elements are made with consistent uniformity using the latest in manufacturing techniques. MECS QC relies on various methodologies to measure fiber bed properties, including but not limited to: velocity profiles, matched flow resistances, and dry bed manufacturing pressure drop measurements. Finally, continued investment in research and development programs help create new inventions and innovations that bring more value to clients. In conclusion, world-class mist eliminator performance in sulfuric acid service is a result of using theoretically sound, semi-empirical design models that have been field-verified over many years. Optimum performance is maintained by providing proper designs, unwavering attention to manufacturing techniques, quality control, continuous improvement and customer support. For more information, please visit www.mecs.com. q

ReferencesDzyaloshinskii, I. E.; Lifshitz, E. M.; Pitaevskii, Lev P. (1961). General theory of van der waals forces, Soviet Physics Uspekhi 4 (2): 153.Mullin, Benjamin J.; Agranovski, Roger D.; Ho, Chi M., Effect of Fiber Orientation on Fiber wetting processes, Journal of Collid and Interface Science, July 2003, pp. 449-458.Einstein, Albert, Investigations on the Theory of the Brownian Movement, 1905, BN Publishing, 2011 edition, pp. 10-12.Mills, Anthony, Heat and Mass Transfer, CRC Press, 1995, pp. 899-900.Cheng, Yung-Sung; Allen, Michael D.; Gallegos, David P.; Yeh, Hsu-Chi; Peterson, Kristin, Drag Force and Slip Correction of Aggregate Particles, Aerosol Science and Technology, 1988, pp. 199-214.

Fig. 6: element seal legs routed to distributor troughs.

Fig. 7: More space under elements using autoDrain.


Fe

atu

re

Sulfur pits are a common sight at oil refineries, sulfuric acid plants, petrochemi-cal plants, fertilizer plants and chemical facilities. Sulfur is melted in the pits to prepare it for manufacturing sulfuric acid or other by-products, as an aggregate for fertilizer products or simply for sale on its own. No matter what the reason for the sul-fur pit, it needs a protective lining to make sure the sulfur, as well as the gases gener-ated at the pit, do not attack and destroy the containment structure. Most sulfur pits are made of concrete, although steel is another option. The gases generated at a sulfur pit, when mixed with the humidity in the environment, will condense into sulfu-ric acid (H2SO4), which is very harmful to unprotected concrete or steel. When burned and exposed to oxygen, sulfur creates sulfur dioxide (SO2), a yellowish, viscous liquid that is soluble in water at all concentrations. It can also come in the form of a toxic gas. The classic protec-tive lining installed at a sulfur pit uses a high-temperature resistant membrane, acid resistant brick and an acid resistant mortar. Duro-Type III brick is the best for any acid immersion conditions, due to its low porosity and low water absorption. The mortar needs to both be acid resistant and have the ability to resist high temperatures that are common in sulfur pits. Potassium silicate-based mortars are the best in this situation. There are also gunite versions of the potassium silicate mortar, which make the application process much faster and less expensive than the brick lining system. Either can be an effective solution. In some cases, the selection of a calcium aluminate mortar/gunite system is dependent on the pH level in the pit. A commonly used practice is the addition of limestone and other alkaline products to curb the pH of the pit and assist with con-trolling the acidity as a means to protect the concrete/steel surface. There are disad-vantages to this system, however. In these cases, because the pH of the pit has been raised above 7 on the pH scale, the use of potassium silicate products are not recom-mended, because the potassium silicate is resistant to exposure to pH from 0 to 7. But when the pH is higher than 7, the potassium silicate is damaged and the lining will fail prematurely. Another option is a calcium aluminate mortar/gunite product. Calcium aluminate will resist any exposure to pH from 3.5 up to 13, which makes it the pre-ferred solution to replace potassium silicate as a protective lining. Why not use sodium silicate, which was the original solution so many years ago? Sodium silicate, when exposed to sulfuric acid, will react and create a globu-lar salt, which has the tendency to keep growing inside the matrix of the sodium

silicate exposed to the sulfuric acid. When the salt grows, it generates cracks in the lining. The lining will spall and fail, expos-ing the surface to attack by sulfur on one side and acidic condensates on the other. Sodium silicates have been surpassed as a mortar for acidic applications since the late 1940s early 1950s, when potassium sili-cates became the preferred mortar for this application. Although potassium silicate is also a silicate, and therefore reacts with sulfuric acid to form a salt, it is a stable salt that doesnt grow, and therefore will not damage the lining. Pittsburgh-based Sauereisen is known as the source for references and engineered solutions for the restoration and corrosion prevention of sulfur pits. With 117 years of experience, this third-generation com-

pany has grown into one of the best-known corrosion-resistant materials manufactur-ers in the world, with a product portfolio that includes a complete line of organic and inorganic corrosion-resistant materials for new and rehabilitation applications. A customer in Israel had experienced repeated problems maintaining several large sulfur pits. Restoration attempts included removing all the deteriorated con-crete, placing forms and pouring new port-land-based concrete. This was a large and expensive undertaking requiring extended periods of downtime. More importantly, the solution would often last for only one or two years, before it needed to be repeat-ed. They finally contacted Israel Paycher, owner of Sealtec Construction Co. Ltd of Israel and a Sauereisen representative, for a long-term solution for rehabilitation and corrosion protection. Paycher contacted Luis Granes, the Sauereisen International Sales Manager for Israel, to come up with a viable solution to the corrosion issues at this sulfuric acid facility. After taking into consideration maximum service temperatures, exterior climate, humidity, structural components and pH levels, Granes recommended a dual lining system of Sauereisen Membrane No. 89 and Sauereisen Gunite Lining No. 35 castable, due to their excellent performance in such adverse, corrosive and demanding conditions. The recommended dual lining system included a high temperature single compo-nent, asphaltic membrane for a corrosion resistant monolithic lining at 125 mils (1/8-inch thickness). No. 89 is easily applied by airless spray equipment, and provides a second layer of defense for penetration of gasses and liquids to the substrate. This flexible coating is resistant to acids, alkalis and salts associated with flue gas environ-ments and substrate movement from tem-perature changes or other causes. It also maintains excellent elasticity and adhesion to both concrete and steel substrates over a temperature range of 60-300 degrees F (53-149 degrees C). Sauereisen chemical-resistant castable no. 35 is a gunite-grade, hydraulically-setting, calcium-aluminate cement. No. 35 is recommended for protection of concrete and steel surfaces from high tempera-tures, thermal shock, abrasion and chemi-cal attack by mild acids or alkalies. It can eliminate costly acid-brick linings and is equally effective for new construction or rehabilitation projects. This chemical-resistant lining resists alkalis over a pH range of 3.5 to 12.0 and withstands temper-atures up to 2100 degrees F (1149 degrees C). No. 35 has excellent thermal shock resistance, develops high strength quickly with low shrinkage and is non-corrosive in direct contact with concrete, iron and steel.

aggressive corrosion and demanding conditions need aggressive solutions

Continued on page 21

effects from an improperly lined sulfur pit.

Sulfur pit after one year of continuous service.

gunite lining no. 35 over high temperature membrane no. 89.

Sulfur pit restored completely with Sauereisen no. 89 & no. 35 gunite.

Spray-applied membrane no. 89.

potassium silicate lining no. 54-gunite.

potassium silicate lining showing signs of deterioration due to higher levels of pH in a sulfur pit.

By: Luis F. Granes and John E. Davis, Sauereisen


Fe

atu

re

Vancouver-based NORAM Engineer-ing and Constructors Limited worked with a client located in southern California to develop a project execution strategy to modernize a sulfuric acid plant. The plant had a number of pieces of equipment ap-proaching end of life and suffered from some technical issues. The plant, a 450 STPD (as 100 percent H2SO4) sulfuric acid regeneration plant, utilizes single ab-sorption technology followed by a tail-gas scrubber. Gas handling and conversion equipment was replaced in three separate shutdowns over a period of over five years (the final step of the project was completed in November 2015). The plant required the replacement/upgrade of a four-bed catalytic converter, three gas-to-gas heat exchangers, a gas preheater, a preheater gas-to-gas heat ex-changer, most of the gas ducting, acid tower packing, instrumentation, SO2 con-

version catalyst, as well as other ancillary equipment. Essentially all the gas handling equipment was replaced by modern equip-ment designs that provide higher reliability, lower pressure drop and lower SO2 emis-sions. This paper focuses on the results of the most recent project step.

upgrade strategy Defining the scope and schedule of a major plant upgrade was a complex task. Several factors were taken into consid-eration, including budgetary constraints, turnaround planning, duration of plant shutdown, lost production, technical risk, mechanical conditions of existing equip-ment, space availability, permitting, logis-

tic considerations and the time required for fabrication and installation of major equipment. The plant upgrade strategy was devel-oped to replace the equipment that was in the worst mechanical conditions. The fol-lowing was considered as the basis for the upgrade:1. New equipment to be fabricated utiliz-

ing better materials than existing: a. Gas handling equipment was

built with stainless steel alloys such as SS 304H, which provide higher corrosion resistance than carbon steel.

b. Replacement acid tower packing was made of slip cast ceramic, which is mechanically stronger than conventional packing.

2. New equipment to be safer and more ergonomic than existing:

a. Utilized improved design, reduc-ing the chances of developing leaks.

b. When possible, due to permitting issues, the new equipment al-lowed for better access.

3. New equipment to have lower pressure drop, thus saving electrical consump-tion of the main blower:

modernization of a sulfuric acid plant in three easy steps

Also, no. 35 is safe to use and does not emit toxic or hazardous fumes or odors during mixing, application or setting. Visual inspections were done on sulfur pit no. 10 over the next few years, which showed the pit to be in good condition. When the customers maintenance personnel opened pit no. 10 for inspection and maintenance five years after Sealtec restored it using Sauereisen no. 89 and no. 35 dual pro-tective lining system, they were pleas-antly surprised by what they found. The pit was in excellent condition. After the inspection was complete, the pit showed no damages or deterioration, a far cry from the normal rehabilitation needed every 1-2 years with previ-ous materials. The only problem to be found was a crack in the floor, which, according to Paycher, was never pro-tected. The facility is currently setting up to fix this problem, again employing Sauereisen products. This plant has been using Sauereisen materials for the last 10 years in other production areas

of the plant without a single complaint or failure. Currently the facility is construct-ing a new, larger sulfur pit and plans to institute a corrosion-preventative pro-gram. After construction, the pit will be lined with the Sauereisen dual-lining system that was used in the rehabilita-tion earlier, before placing the pit into service. Sauereisens 117 years of experi-ence in corrosion control is working for customers. The company maintains a global presence with a network of technical sales representatives through-out the world, and with manufacturing and warehouse facilities located in the United States, Europe, the Pacific Rim and Latin America providing world-wide product distribution. Sauereisen remains dedicated to solving problems requiring specialty materials with expertise in infrastructure restoration and corrosion prevention. For more information, please visit www.sauereisen.com. q

Continued from page 20

NORaM preheat Heat exchanger

NORaM Hot Heat exchanger

Ducting NORaM Cold Heat exchanger

3-D model of the upgrade strategy for steps 1 and 2.

Steps 1 and 2 involved replacement of several key pieces of equipment.

3-D model of the upgrade strategy for step 3.

By: Andres Mahecha-Botero, Brad Morrison, Brian Ferris, Hongtao Lu, J.P. Sandhu, C. Guy Cooper and Nestor Chan, NORAM Engineering and Constructors Ltd.


Fe

atu

re

a. Used gas-to-gas heat exchang-ers with radial flow designs that provide lower pressure drop than older designs.

b. Ducting sizes were reviewed for lower gas pressure drop.

c. Used high performance (HP) packing to reduce gas side pres-sure drop to half of the existing saddle packing.

4. New equipment to provide better re-liability, longer on-stream time and lower maintenance requirements than existing:

a. All pieces of equipment utilized modern designs.

b. All-welded equipment used to eliminate leak points.

c. Thermal expansion strategies re-viewed to eliminate trouble areas.

d. Split-flow gas-to-gas heat ex-changers utilized for improved equipment reliability.

5. New equipment to allow for lower emissions of SO2:

a. The catalyst loadings of the con-verter were increased.

b. All the old catalyst in the convert-er was replaced by new.

c. Some cesium promoted catalyst was added to the converter to in-crease the SO2 conversion at low temperatures.

d. The converter preheater was im-proved to allow for faster preheat-

ing at higher temperatures. e. A multi-bed preheating system

was installed to allow for the re-duction of start-time and up emis-sions.

f. All these lower emissions have a side benefit of better operability of an existing tail gas scrubber.

With all the considerations above, and taking into account the conditions of the existing equipment, shut-down time and maintenance budgets, the following staged approach was developed: Step 1 (2010) InstalledoneSFSplitFlowPreheat

heat exchanger and ancillaries. Installed oneRFRadial FlowHot

heat exchanger. Installedallstainlesssteelductingto/

from converter.Step 2 (2013) InstalledoneRFRadialFlowCold

heat exchanger. InstalledoneRFRadialFlowInter-

mediate heat exchanger. Installedallstainlesssteelductingbe-

tween heat exchangers.Step 3 (2015) Installedstainlesssteelconverterwith

new catalyst and improved instrumen-tation.

Installed converter preheat ductingsystem.

InstalledHPpackinginthedrytower.NORAM completed an acid plant opti-

mization study for the facility. Moreover, NORAM provided the basic design, de-tailed engineering, site services and fabri-cation advisory services for all the equip-ment replacement projects.

execution of step 3 The final step took place in 2015. This step focused on the upgrade of the conver-sion system. A new converter was fabri-cated by NORAMs own fabrication shop in Axton, Vancouver. The converter was made of all-welded stainless steel 304H with catenary plates (no posts). The walls of the converter were -inch thick. The new converter was crafted to match the ex-isting permits and tie-points. The converter, grillage and ducting were transported in one piece to the site. The vessel was lifted at the fabrication shop and rolled into a barge at the shop dock. The barge was then towed by a tug boat to

the main port. The converter was lifted by the on-board cranes of a cargo ship. The old converter was removed in one piece and the new converter was successfully installed during a regular plant turnaround.

Conclusion This project highlights NORAMs ability to meet and exceed the clients ex-pectations to modernize the complete gas-side of a sulfuric acid plant. In this case, the project was successfully executed in three steps, achieving improved reliability, lower pressure drop, improved ergonomics and lower emissions. NORAM Engineering and Construc-tors Limited performs engineering studies and training and supplies improved equip-ment at attractive prices for sulfuric acid plants. For more information, please visit www.noram-eng.com. q

Completed converter walls. The catalyst support plate for the new converter.

The bottom of the newly-constructed, all stainless steel converter.

The old converter, after removal from the site. The new NORaM converter after installation.

The converter was placed on a barge for transportation.Loading the newly constructed converter at the dock.

Spring Summer 2016

Documents

Transcript of Spring Summer 2016