### The photographs on the cover are an exampl e of an aluminum furnace featured on the Harbison Walk er web page (top), cathodoluminescence of a fusion-cast spinel refractory (center), and cathodol uminescenc e of a fus i on-cast alumina refractory( bottom).

1

# Refractories for Industrial Processing: Opportunities for Improved Energy Efficiency

Jam e s G. Hemr ick,* H. Wayne Hayden, † 

### Peter Angelini,* Robert E. Moore, § 

### and W illiam L. Headrick §



### *Oak Ridge National Laboratory † 

### Metals Manufacture, Process, and Controls Technology, Inc. § 

### R. E. Moore and Associates

January 2005

Prepared for the DOE-EERE Indus trial Technologies Program

## Table of Contents

List of Figure s and Tables

..................................................................................................... .......... v Executive Summary

.............................................................................................................. ........ vii Abbreviations and Acronyms

..................................................................................................... .... ix
1. Introduction

................................................................................................................... .......... 1 2. Current Refractory Status

...................................................................................................... . 1 2.1 Usage in Industry

......................................................................................................... 4 2.2 Current R&D Status

..................................................................................................... 4 3. Esti m ated Metrics for Overall Energy Savings Opport unities

............................................... 5 4. Process Technology and Perform ance Barriers

...................................................................... 7 4.1 Kilns and Calciners

...................................................................................................... 7 4.2 Reverberatory Furnaces

............................................................................................... 8 4.3 Boilers and Reactor Sy stems

..................................................................................... 10 4.4 Gasifiers

..................................................................................................................... 1 3 5. Overall R&D Barriers and Pathway s for Refractories

.......................................................... 15 6. Specific R&D Areas with Barriers and Pathway s
................................................................ 17 6.1 Im proved Castable and Monolithic Refractory

.......................................................... 17 6.2 Modified Fiber Materials

........................................................................................... 17 6.3 Surface Modification (Coatings, Phy s ical or Therm a l Alteration)

............................ 17 6.4 Synthetic Aggregates and Powders

............................................................................ 18 6.5 High-Tem p erature Properties of Refractories

............................................................ 18 6.6 In Situ and Graded Refractories

................................................................................. 19 6.7 Sensors for Materials Performance

............................................................................ 19 7. Referen ces
..................................................................................................................... ........ 22 Appendix A: Discussion of Refractory Usage by Process Industries

........................................... 26 A.1 Alu m inum

.................................................................................................................. 26 A.2 Cement and Lim e
....................................................................................................... 30 A.3 Chem ical and Petrochem i cal

...................................................................................... 33 A.4 Forest Products

.......................................................................................................... 35 A.5 Glass

.......................................................................................................................... 37 A.6 Heat-Treating and Anneal ing

..................................................................................... 40 A.7 Iron and Stee l

............................................................................................................. 41 A.8 Metal Castin g
............................................................................................................. 44 A.9 Referen ces fo r Appendix A

....................................................................................... 48 Appendix B: Rotary Kiln Analy s is Schem atic, Conditions, and Re sults

..................................... 50 Appendix C: Reverberatory Furnace Schem atics

......................................................................... 56 Appendix D: Reverberatory Furnace An aly s is Condit i ons and Results

........................................ 58 Appendix E: Boiler Schematic

................................................................................................... ... 62

iii

## List of Figures and Tables
Figures
ES.1. Tem p erature regim es for industr ial appl ications of refractories

..................................... vii 1. Long-term en ergy benefit opportunities estim ated for the four anal yzed furnace types
................................................................................................................. ..... 6 2. Im proving ref r actory m aterials for im proved energy efficiency

..................................... 16 B.1. Longitudinal section of a typical rotar y kiln

.. ................................................................. 50 C.1. Reverberatory furnace schem ati c
..................................................................................... 56 C.2. Typical reverberatory alum inum

- m elting furnace

........................................................... 57 E.1. Boiler furnace sections

................................................................................................ .... 62



### Tables
1. Types of furnaces utilizedi nAmerican industr y
............................................................... 2 2. Refractory barriers for furnaces utilized i nAmerican industr y
.......................................... 3 3. Energ y anal ysis by i ndustr y withestimated short-term and long-te rm energy savings opport unitie s fro m im proved refractories

.................................................. 5 4. Total effect of im proved refractories on rotary kilns

......................................................... 8 5. Total effect of im proved refractories on reverberatory furnaces

...................................... 10 6. Stea m sy ste masse ss ment tool single header analy s is results for i m proved insulation for im proved boiler efficiency

......................................................................... 11 7. Stea m sy ste masse ss ment tool single header analy s is results for i m proved pipework ins u lation for im proved steam transfer sy stems

............................................... 11 8. Potential energy savings fr om i m provedboiler efficiency due to improved refractories and im proved transfer pipe-work insulati on
................................................. 12 9. Renewable energy generation pote ntial (billion kWh/ y ear) from black liquor inthe pulp and paper industry inthe southeastern Unit ed States

..................................... 15 10. Reco mmended R&D pathway s for advanced refractories

............................................... 20 A.1. Feedstock for energy use in the cem e nt industr y , 1993-2001

.......................................... 32 A.2. Estim ated en ergy use in melting and ref i ning

.................................................................. 38 A.3. Conversion of North Amer ican glass melters to oxy

- f u el firing as of 1998 and a s of 2004

..................................................................................................... 39 A.4. Process and energy data fo r U.S. metals casting industry
................................................ 45

v

## Executive Summary

Refractory materials with properties suitable fo r high -tem perature applications are used throughout U.S. industr y as insulation and/or cont ainment vessel li nings in high- t em perature and corrosive environm ents. In deed, it woul d be diffi cult to identif y an industrial process that does not use refrac t ory m ateri als in one aspect or anothe r. These material s m u st not only be capable of perform ing these ta sks at el evated te m p e r atures, but may also be called upon to bear mechanic al loads and transfer heat. Re fractories ar e char acte r ized by two aspects that qualify the m as strategic materials in support of American industr y : (1) their ability to contain he at, chem icals, and m e lt s; an d (2) the cros scutting natur e of their utili ty. Figure ES.1 s hows the ranges of usage tem p eratur es for num erous industr ial appl ications of refractories. This report and the attached a ppendices describe the current furnace technologie s used b y U.S. industries with specific highlightedanal y s is focused on four furna ce types—kil n s/ calciners, rev e rberatory furnaces, boilers and r eactor sy stem s, and gasifiers

— whi c h are co mmon to m u ltiple industries and are representat i ve of areas where significant energy im provement could be made through future refractory im provem e nt. Anal y ses of these four types of furnaces alone suggest potential energy savings of over 400 trilli on B tu/ y ear. In addition t o identify i ng areas of opport unity , th is report describes possible crosscutting resear ch and developm ent (R&D) pathway s for overcom ing refract ory -related performance barriers which could l ead to im proved energy efficiency through both the alterati on of current material s an d practices an d the developm ent of new materi als, furnace designs, or redesigned processes of vary ing sizes.

Fig. ES.1. Te mperatur e r e gimes for in dustrial applications of refractories.

vii

## Abbreviations and Acronyms

BLS black liquor s o lids BOF basic oxy g en furnace Btu British thermal unit DOE U.S. Depart ment of Energy EAF electric arc furnace EERE Energy Efficiency and Renewable Energ y(DOE) FCCU fluidized cataly s t cracking unit ITP Industrial Technolo g ies Pro g ram (DOE) MECS Manufacturing Energ y Co n s u m ption Sur v ey ORNL Oak Ridge National Labor atory R&D research and developm ent TBtu trillion Btu

ixRefractories f o r Industrial Processing



## 1. Introduction

The Industrial Technologie s Program (ITP), part of th e Department of Energ y ’ s Office of Energ y Efficiency and Renewable Energy (DOE-EERE), seek s to im prove the energy intensity of the U.S. industria l sector through a coordi nated program of research and development (R&D), validation, and dissem i nati on of energy effici ency technologies and operating pra c tices. To achieve its m i ssion, ITP partners with industr y , equi p m ent m anufacturers, and other stakeholders to develop te chnologies th at enable industry to u se le ss energy per unit of out put . Refractories are a class of m at e rials of critical i m portance to m anufactu r ing industries with high-te m p erature unit processes. This study describes industrial refr actory applications and identifies refractory performance barriers to energy efficiency fo r processi ng. The report provides rec o mmendations for R&D pathway s leading to im proved refractories fo r energy -effic i ent manufacturing an d processing.


## 2. Current Ref r act o ry Statu s

There are many different types of furna ces usedin industries in the United States, each with different refra ctory needs and challenges. A discu ssion of the refractory issues for several ene r gy intensive processing industries can be f ound in Appe ndix A. Fiftee n classifications of furnaces with several common issues can be identified. T ypical industrial applications of th ese fifteen furnace types are shown in Table 1. Refractory challenges and proble m s relat e d to these furnace types, as reported by industry personnel and discu ssed in detail in Appendix A, are shown in Table 2.
Of these fifte e n furnace types, four are highl ighted in this docum ent: kilns/calciners, reverberatory furnaces, boilers and react ion s y stem s, and gasifiers. These wer e s e lected bec ause they are co mm on to m u ltiple industries and re presentative of areas where significant energy savings [ on the order of tri llions of Btu (TBtu)/y ear] could be realized throughf u ture refractory i m provem e nt. Although emphasis was pl aced on bl ast furnaces, basi c oxy g en f urnaces ( B OFs), and other fur n ace types found i nthe steel industr y , w e have chosen not t o focus on these furnaces because of their design practice of intentionall y l eaking energy so a s to induce a steep therm a l gradient through th e lining. Additionall y, BOF refr actories are known to last thousands of heats, and little im p r ovement is expected in impr oving refractories for these applications. Analy s is and discussion will address refr actory im provem e nts leadi ng to higher e n ergy efficiency and im proved product yield for each of these four furnace types. Discussion will focus on the energy -i ntensive industries of the United States including alum inum , cement and lim e, chemicals and petrochemical s, forestproducts, glass, heat tr eat ment and annealing, iron and steel, and metal casting.

1R e f

ractories f or Industrial Processin g

2Table1.Types of furnacesutilized in American industryFurnace typeIndustrial furnace applicationsAluminumCement &limeChemical/petro­chemicalForestproductsGlassHeat treatIron &steelMetalcastingOtheraBlastfurnaceX1BasicoxygenfurnaceXReverberatoryfurnaceXXXX2Multiplehearth2Ladle/tundishe/troughXXXX3ElectrolyticsmeltingX4KilnsXXXXXX5,6Electricarcfurnace(EAF)X7CupolaXHeattreatXXXXX5,8StillX9Reactor/reformerXBoilerXXXXX10GasifierXXHeatexchangerXXXXXXXXaKey to“Other”:1.Lead6.Mining2.Copper7.Oxidemelting3.Moltenmetalhandling8.Variousmetalproducts4.Magnesium9.Organic and inorganic products5.Ceramics10.VirtuallyallindustriesR e f

ractories f or Industrial Processin gTable 2.Refractorybarriersforfurnacesutilized in American industryFurnace typeRefractorychallengesAbrasionCaking/agglomerationContamination/foulingCorrosion/wearErosionMechanicaldegradationThermalinsulationThermomechanicaldegradation/shockRefractorylife/repairsBlastfurnaceXXXXXBasic oxygen furnaceXXXXXXXReverberatory furnaceXXXXXXMultiplehearthXXXLadle/tundishe/troughXXXXXXElectrolytic smeltingXXXXXKilnsXXXXXXXXXElectricarc furnace (EAF)XXXXCupolaHeattreatStillXXXXXReactor/reformerXXXBoilerXXXXXXXXGasifierXXXXXXXHeatexchangerXXXX

3Refractories f o r Industrial Processing



## 2.1 Usage in Industry Althoughrefractories are used in m o st, if not all, of U.S. ind u stries, the iron an d steel industry consumes 70% of the refractories produ ced gl oball y , while the cement and lime industr y consumes 7%, the ceram i c s industr y 6%, the glass in dustry 3–4%, and the oi l industry about 4%. 1 In 199 8, a sur v ey was cond ucted b y the U.S. Advanced Ceram i cs Association and Oak Ridge National Laborator y (ORNL) to determ ine oppor tuni t i es for advanced ceramic s to m e et the needs of manufacturing in dustries. 2 These industries included alum inu m , che m ic als an d petrochem i cals, forest product s , glass, m e t a ls casting, and steel. Additionall y , th e supporti ng i n dustry of heat treating and annealing was considered. From this surv ey , a num b er of critical are as wer e identified in e ach of these industries where i m pr ovem e nts could lead to substantial econom ic and energy savings.
Additionall y , the general practice of m o st indus tries is to choose fue l types and sources based primarily on cost and availability

. This, in m anycases, leads to variations in fuel quality and purity which will directly i m p act the performance of the refractory materi als used in the respective furn aces. This must be considered when choosing f urnace m aterials an d when evaluating energy efficiency.


## 2.2 Current R&D Status Substantial changes that h ave occurred in refr actories technolog y o v er the past 25 y ears have resulted in crosscutting impacts on a num b er of m anu facturing industries, 2 incl uding the use of fibrous and hi gh-strength p o rous insulati on to reduce energy consum ption in heat-treating furnaces. In the steel industry, the use of resin-bonded MgO-C- m e t a l linings in basic oxygen furnaces significantly increases the nu mber of heat s between neede drelinings, and SiC-based refractories have led to inc r eased furnace life fo r steel blast furnaces. In the glass industr y , the advent of o x y -fuel melting has led to renewed inter est in alternative refractory m a terials that wi ll allow for processing at higher te m p eratu r es and greate r corrosion resistance to high alkali and water-ri ch environm ents. Additionally , many m o re recent ceramic co m positions have received lim it ed evaluation but have not reached maturity or pr oduction status. All of the se events ar e representativ e of industrial process i m pr ovements that can be acco m p lish e d through advances in refractory m a terials, y e t additional im provements could lead to eve ngreater ener gy savings throug hout th e various ind u stries. The choice of refractory materials for a certain a pplication is often dictated by the trade off between cost and perform ance. In the pa st econom ic considerations have led to th e selection of lower cost/poorer perform ing refractories over hi gher performance/higher cost materials. Yet, with rising energy costs, environm ental r e gul ations, and econom ies of scale; higher priced pre m iu m refr actory m ateri als are r eceivi ng renewe d interest and may prove cost effective in many applications for whic h the y we re previousl y deemed unsuitable.

4Refractories f o r Industrial Processing


## 3
. Estima ted Me tr ics fo r Overall Energy Savings Opportunities

Energ y usage in several of the industries and estim ates of potential energy savin g s throug h i m prove m e nt s in refractories are shown in Table 3. The values shown in this table are based primarily on DOE Manufa c turing Energy Cons um ption Survey (MECS) data describing manufacturing energ y cons um ption in th e y ear 19 98. 3 The esti m at es of energy us age affect ed by refractorie s ar e based on evaluation of industry roadm a p docum ents and discussions with industry leaders. Ener gy savings goals are bas e d on the n eeds of the industries and esti m ates for the four typical furnace types (Table 1) used throughout m any of the industries, which are presented in detail in Appendices B, C, and D. These analy ses are based on heat balance studies where the energy su ppli e d to the s y st em through c o m bustion is equal to the s um of (1) latent heat in the furnace exhaust gases, (2) heat lost through th e furn a ce wall s and roofs, and (3) heat required for heating reactan ts to the process t e m p er ature and phase transform ati ons at that tem p erature. T h e achieve ment of theoretical efficiency would require th at item s 2 and 3 be equal to zero. From a practical point of view, perfect effici enc yis not proba ble, but im provements in furnace refractories could help facilitate i m provements of furnace effi ciency beyond the l e vels of present technology. The projected saving oppor tunities inthe range of 166 TBtu/Yr to 830 TBtu/Yr are equivalent to the y early res i dential electr i cal u sage of New York sta t e and the y early residential air conditioning usage of the US, respec tively

.
Table 3. Ener gy analysis b yindus try with es tim a ted sh ort-term and long-term ener gy s avin g s opportunities from impr ove d refr a ctories
E n erg y s avi n g s g oal s f o r
Indus try NAI CS codes To ta l T B t u/ye ar a U s ag e af f e ct ed by refrac t ories
Percent TBtu/Yr improved re fr actories (TBtu/Yr) Near -ter m 2% Long-term 10% Al um i num 33 1 3 X X 1 44 1 90 % 39 7 7. 9 39 .7 C h em i c al 32 5 X X X 3, 70 4 50 % 1, 85 2 37 .0 18 5. 2 Fabricated m e tals b 33 2 81 44 5 90 % 40 1 8. 0 40 .1 For e st p r od uct s 32 1 X X X , 3, 24 8 40 % 1, 29 9 26 .0 12 9. 9 3 22X XX Fo un dri e s 33 1 5 X X 23 3 90 % 21 0 4. 2 21 .0 Gl ass 32 7 2 X X 20 3 70 % 14 2 2. 8 14 .2 Ir on& st eel 33 1 11 1, 67 2 85 % 1, 42 1 28 .4 14 2. 1 Petrole um & coal 32 4 X X X 3, 62 2 50 % 1, 81 1 36 .2 18 1. 1 pr o duct s St one , cl ayp r o duct s c 3 27X XX d 76 6 10 0% 76 6 15 .3 76 .6 All 14 ,3 3 4 — 8, 29 9 16 5. 8 82 9. 9

a TBtu = tr ill ion Btu/ year
. Source: U. S. Department of Energy , En erg yInformation Administration , 1998 MECS Consumption, Table N3.2, Fuel Consumption, 1 998. b Includes h eat tr eatm e nt

. c Prim aril y cem e n t and lim e
. d Exclud es categ o r yfor glass, 37 27XX.

Additionall y , one m u st con s ider that declines in certain properties may have a di rect influence on other related properties. This is evident for ex a m ple in a furnace wall where lac k of corrosion

5Refractories f o r Industrial Processing

resistanc e may result in a reduction in therm a l efficien cy as decreas es in wall thickness due to corrosion will lead to decreased insulating ability of the furnace wal l . The furnace efficiency will now not onl y be im pacted, but thi nnin g of the re fract ory wall may also lead to shut-down of the furnace for maintenance causing loss of production an d the need for additional energy t o reheat the furnace. Energy conside r ations from a ll these are a s are consider ed in Table 3. Figure 1 shows the potential energy benefit opportunities represe nted by the four furnace types analy zed.

Fig. 1. Long- t erm energy benefit opportunities estimated for th e four analyz ed furnace type s.

6Refractories f o r Industrial Processing



## 4. Process Technology and Performance Barriers

4.1 Kilns and Calciners Kilns and calciners, or the products pro d u ced b y them, are used in many in dustri es (alu m i nu m, cement, chemical, forest products, glass, iron and steel, and m i ning) and therefore have crosscutting interests. Anal y ses were per f orme d to evaluate cases for both alum ina and lime calcinations, based on use of rotary -typ e kiln s for various flame te m p eratures, e xhaust tem p eratures, and wall/roof losses (Appendix B). Fo r all the heat supplied by com bustion, the gross available heat is cal c u lated from th e heat c ontent of the flame less the heatcontent of the exhaust gases , and a part of the heat supports wall lose s while the re mainder is av ailable for the work of the k iln/calcinations of feed to product.
4.1.1 Industrial Applications of Process Technology Alu m inum — alu m ina, carbon, lim e Glass - li me Cement and lim e — lime, cement Iron and steel - lime Chem ical and petrochem i cal — lim e Mining — raw m aterials Forest produc ts — lim e
4.1.2 Current Tec hnology Two types of kilns typicall yfound in the industri es listed were selected for review. In the case of alu m ina calcination, we considered a kiln m e asuring 3.5 m in diameter by 80 m long with an output of app r oxim ately 2 5 0 ,00 0 tons/ y e ar; for lim e calcinations, we chose a kiln measuring 5 m in diam eter by 50 m long with an outp ut of appro x imately 3 65,0 0 0 tons/ y ear. In the lime calcination process, product is often lost through dust l o ss as loose powder is blown out of the kiln along with the exhaust gases. Theref ore, in the lime analy s is, both the case of no dust and the
m o re realistic condition of up to 20% of the cal cined product being l o st as dust were considered. Calculated heat of reactions (at 77°F) of 634 Btu/l b an d 13 64 Btu/l b were used for the alum ina and lim e calc i nation processes, re specti v ely, leading to a calculate d total heat requirement of 1728 Btu/lb f o r the alum in a calcination process and 2196 Btu/l b for the lime cal cination proc ess.
4.1.3 Energy Im pact Energ y benef its resulting f r om refractories in kilns are related to the following operational im provem e nts:
1. An increase i nthe adiabatic flame tem p eratur e of 200°F (as with m odified oxy-fuel firing at about 2 0 % enrich m e nt) canlead to subst antia l fuel savings d u e to th erm a l efficiency

. 2. A decrease inthe exhaust t e m p erature of 200° F (result ing in greater heat retained for the actual proces s) also leads t o a substantial fuel savings. 3. A decrease inwall/roof losses of 200,000 Btu/to n of product can r esult in subst antial energy savings (considering half th e supplied e n erg y go es up the stack, with the remainder available to support work and wall losses). 4. Process y i eld i m provem e nt s will resu lt in substantial energy benefits. For the energy analy ses, it was assu med that a little over half of the total calcined alum ina produced in th e United States (4.4 m illion m e tric to n s in 2001) was produced us ing a rotar y kiln. Sim i larly , it was assu med that of the 20 million short tons of lim e produced in th e United States

7Refractories f o r Industrial Processing

in 20 02, ab out 80% of the productio n w as perform ed using rotar y k iln calciners. It was also
assu med that 80% of the 103 m illion metric tons of cem e nt produced in the Unit ed States in 2002 was produced using rotar y kilns operatin g in the te m p erature range of 260 0 to 30 00°F. Results of the analy s is are shown in Table 4.

T a bl e 4. T o t a leffec t of i m pr ove d re frac tor i es on ro tar y ki l n s Energy-intens ive process indus tries Prod uct Fuel decre ase (Btu/t on ) Wa ll lo ss decrease (Btu/t on ) To ns a f fected per ye ar Energy be nefi ts per ye ar (TBtu)
Al um i num Al 2 O 3 41 3, 0 00 20 0, 0 00 2, 50 0, 0 00 1. 5 C e m e nt and l i m e C e m e nt 80 0, 0 00 20 0, 0 00 82 ,4 0 0 , 0 0 0 82 .4 Ce m e nt and lime,

chem ical and petr ochem i cal , fo rest pr od uct s , gl ass, i r o nan d steel Lim e : N o dust 20 % du st 41 3, 0 00 88 5, 0 00 20 0, 0 00 25 0, 0 00 1 6 ,000 ,0 00 1 6 ,000 ,0 00 9. 8 18 .3

All 11 2 a

a Without carbo n and sulfur contributions. Source: Portland Cement Association, Economic I ndustry Overview, 2003.

4.1.4 Barrier s Rel a ted to Refr acto ry Materials for Kilns and Calciners The central c onclusion from the analy ses for c oncerning kilns and c a lciners is tha t as fla m e te m p erature s increase and exhaust te m p eratures appr oach process te m p erature s , greater thermal efficiency is realized. Hence, im provem e nt s in reducin g the therm a l conductivity of the refractories, and im proving the chem ical and m e chan ical properties of the refract ories, will have a significant payoff in overall fuel consumption. Addressing the following barriers associat ed wi th the performan ce of refract ory m ate rials used in kil n s and calciners would im prove energy efficiencie s
. 1. Unavailability of refractories with sufficien t high-temperature stren g th, erosion/c o rrosion resistance, creep resist ance, r esistance to large tem p erature gr adients, and stability at higher te m p erature s for use with elev ated furnace fla m e te mperatures. 2. Lack of sufficient high-te m p erature durability and c o rrosion/erosi on resistance in current refractorie s for im proved heat transfer th rough increased levels of sti rring and a g itation of the materi al being processed. 3. Unavailability of refractories with lower th ermal conductivity and greater high-tem p erature stability needed to achieve substantial reductions in wall and roof heat losses. 4. Lack of know ledge concerning o p eration s need ed to in crease refractor y life, redu ce product sticking, and increase l e vel s of product recove ry for the reduction of unschedule doutages, i m prove m e nt of product y i eld, and the increas e of furnace ca mpaig nlives.



## 4.2 Reverberatory Furnaces Analy ses of reverberatory furnaces were performed to evaluate cas es of alum inu m , copper, and glass- melting furnaces for various assumed values of flam e temperatures, exhaust tem p eratu r es, and wall/roof losses. For all the heat supplied by co m bustion, the gross available heat is the heat

8Refractories f o r Industrial Processing

content of the flam e less the heat content of th e exhaus t gases. Additionally , part of the gross available heatsupports wall losses and the rem a inder supports m e lt ing, the real j ob of th e furnace. Reverberatory furnace sche m ati cs ar e provided in Appendix C.
4.2.1 Industrial Applications of Process Technology Alu m inum — m e tal melt ing Metal casting — m e tal mel ting Glass — glass m e lting Copper — metal m e lting Iron and steel — m e tal melting
4.2.2 Current T e c hnology Analy ses of reverberatory furnaces we re basedon a nom i nal furnac e having a capacity for melting 20,0 0 0 lb of m aterial per hour. T h is is a typical size used in the alum inu mindustr y an d is used for the other industrial analy ses for co m p arison purposes. For th e fixed m e lti ng capacity of 20,000 lb/ h , th e energy needed for m e lti ng is th e same in all alum i num melting cases, 504 Bt u/lb. In the analy s is, wall and roof losses from 0 (rea lly im possible) to 10 m illion Btu/h, or 0 to 500 Btu/l b of material, hav e been assu med. This range is expected to span the full spectru m of industrial pra c tice. The gross available h eat to do thes e jobs is the d i fference in flam e and exhaust heat contents. It has been assu m e d that natural g as fuel with an adiabatic fla m e t e m p erature of ~3600°F has been used as a base, with increasi ng flame tem p eratu r es that m ay be achieved throug h regen e rators/recup e rators or ox ygen enrichment.
Exhaust tem p eratures rangi ng from 1400 to 2000° F have been assumed. Increasing exhaust te m p erature s at fixed fla m e te m p erature s r esults in tot a l heat consum ptions ranging from 777 Btu/l b (61% therm a l efficiency ) to 2261 Btu/lb ( 22.3% thermal efficiency ). Furnaces in the alu m inum in dustr y generally fall in this range, as summarized bel o w: Furnace type Thermal efficiency Norm al furnace (poor to good practices) 2500–1350 B tu/lb State-of-the-art new furnace 1350–1200 B tu/lb Furnace builders’ lower limit for reverb. 1200–1000 B tu/lb New/radical technolog y 1000 –50 4 Bt u/lb
Sim i l ar effici encies ar e ex pected inthe other two industries studied.
4.2.3 Energy Im pact Energy benefits that could result from i m proved refr actories in re verberatory furnaces are r e lated to the foll owing o p erational im provements:
1. An increase i nthe adiabatic flame tem p er ature of 200°F (e.g., oxy-fuel firing w ith 20% oxy g en) leads to substantial fuel savings due to therm a l efficiency

. 2. A decrease inthe exhaust t e m p erature of 200° F (result ing in greater heat retained for the actual proces s) also leads t o a substantial fuel savings. 3. A decrease inthe wall/roof losses of 2.5 milli on Btu/h also results in substantial energy savings (considering half th e supplied e n erg y go es up the stack, with the remainder available to support m e lting and wall losses). For the calculations, it was assu med that annuall y in the United States, 9.3 billi on lb of alum inum (half of all the ingot and mill products in the alum inum industry in 1998) are m e lted in reverberatory furnaces, 0.36 billion lb of refined copper fro m scr ap is processed i nreverberatory

9Refractories f o r Industrial Processing

furnaces, and an average of the 40 billion lb of glass is produced us ing reverberator y furnaces (based on 1999 num b er s). In addition, 20% oxy g en e nrichment was assu med for the metal melting cases, while 100% oxy g en enric h ment was assu m e d for the glass m e lting case. The details of the calculations ar e presented in Appendi x D. Results of the analy s is are shown in Table 5.

T a bl e 5. T o t a leffec t of i m pr ove d re frac tor i es on rever be rator yfurnac es
Energy-intens ive process indus tries Prod uct Fuel decrease (Btu/lb) Wa ll lo ss decrease (Btu/lb) Poun ds a f

f e c t ed p e r year ( × 10 9 ) Energy be nefi ts per ye ar (TBtu)
Al um i num , coppe ra
Gl ass

All M e t a l m e lt i ng
Gl ass m e l t i ng 45 2
47 6 20 0
10 0 10
40 2 (2 0% e nrichm e nt) 76 (1 0 0 % e nric hm e nt) 78

a Without iron and steel and metal casting contributions Sources: Am eric an M e t a l M arket , Metal Statistics 1998, 90th ed., 1998; DOE Office of Industrial Techno logies, Energy and En vironmen tal Profile of th e U.S

. Gla ss Industry, 200 2.

4.2.4 Barrier s Rel a ted to Refr actory Materials for Reverberatory F u rnaces The central c onclusion from the se analy ses is that as f l a m e te mpera tures increas e and exhaust te m p erature s approach process t e m p er atures, greater th erm a l effi cie n cy is realize d . As shown in Appendices B, D, and E, the im pact of reducing wall losses by 2.5 million Btu/h leads to corresponding savings of 4.5 m illion Btu/h for alum inum (232 Btu/lb), 7. 5 m illion Btu/h for copper (333 Btu/lb), and 11.9 Btu/ h for glass ( 595 Btu/lb). Hence, i m provem e nt s in reducing the therm a l conductivity of th e refractories, and im pr oving the chem ical and m ech anical properties of the refractori es, will have a significant payoff in ove rall fuel consum ption. Addressing the following barriers as sociat ed with the perform anc e of refractory materials us ed in reverberatory furnaces would im prove energy efficiencies.
1. Unavailability of refractories with sufficien t high-temperature stren g th, erosion/c o rrosion resistance, creep resist ance, r esistance to large tem p erature gr adients, and stability at higher te m p erature s for use with elev ated furnace fla m e te mperatures. 2. Lack of sufficient high-te m p erature durability and c o rrosion/erosi on resistance in current refractorie s and m ateri als f o r im proved heat tran sfer th rough increased levels of stirring and agitation of the material b e ing processe d. 3. Unavailability of refractories with lower th ermal conductivity and greater high-tem p erature stability

. 4. Lack of know ledge concerning the i n ter actions between refractories and process environm ent/operations which leads to reduced refractory life, pro duct sticking unscheduled outages, low product yield, and lim ited f urnace cam p aign lives.


## 4.3 Boilers and Reactor Systems Boilers and reactor sy stems are found in m o st indus trial settings and therefore are of ke y inter est as a cros scutting unit process. For the following anal y s is, boilers for the production of stea m ar e considered for the alum inu m , cement and lim e, ch emical and petrochem i ca l, forest products, and

10Refractories f o r Industrial Processing

heat treat ment industries. ( S ee Appendix E for a schematic illustrat i on of boiler f urnace sectio ns.) Additional areas for energ yefficiency im proveme nts also exist in chem ical reactors utilizing cataly s ts and other reactions.
4.3.1 Industrial Applications of Process Technology Alu m inum — steam production Forest produc ts — steam production Cement and lim e — steam productio n Heat treatment — steam p r oduction Chem ical and petrochem i cal — steam production
4.3.2 Current Tec hnology For the purpose of the performance anal y ses of bo ilers, a standard unit using a single header boiler s y ste mhas been ass umed.
4.3.3 Energy Im pact Im proved refractory practice in boilers will result in energy benefits either fro m im proving the boiler efficiency through i m proved vessel insulation and/or by reduced heat losses during steam transfer through im proved transfer pipework insulati on.
The DOE Be st Practice s S t ea m Sy ste m Asse ss ment Tool was used to analy ze the effects of im proving bo iler efficiency from 85 to 8 7 % throughu se of the follo wing:

• Im proved ins u lation for im proved b o iler efficiency

• Im proved pip e work insulation for im proved steam transfer sy stem s
The effects of increasing boiler efficienc yby 2% and reducing heat losses during stea m tr ansfe r b y 1 0 % are shown in Tabl es 6 and 7.

Table 6. Ste a m sys t em asse ssment toolsingle he adera n al ysi s resul t s f o r i m pr ove d i n sul a ti on forimproved boiler efficiency 85% efficient 87% efficient Vari able boiler case boiler case Improveme nt Fuel c o st , $ 1 0 0 0 /y ear 4, 00 0 3, 90 8 92 (2 .3 0% ) Fuel c o n s um pt i on, st d ft 3 /h71 ,4 2 1 69 ,7 9 9 1, 62 2 (2 .2 7% ) CO 2 em i ssi ons, 1 0 0 0 l b /y ear 66 ,4 0 3 64 ,8 7 6 1, 52 7 (2 .3 0% ) NO xem i ssi ons , 1 0 0 0 l b /y ear 13 1 12 8 3 (2 .2 9% )

Table 7. Ste a m sys t em asse ssment toolsingle he aderanalysis results for impr ove d pipework insulati on for improved s t e a m tr ans f er s y s t ems Current 10% Vari able oper ati o n improvement Improveme nt Fuel c o st , $ 1 0 0 0 /y ear 4, 00 0 3, 92 4 76 (1 .9 0% ) Fuel c o n s um pt i on, st d ft 3 /h71 ,4 2 1 70 ,0 6 5 1, 35 6 (1 .9 0% ) CO 2 em i ssi ons, 1 0 0 0 l b /y ear 66 ,4 0 3 65 ,1 4 2 1, 26 1 (1 .9 0% ) NO xem i ssi ons , 1 0 0 0 l b /y ear 13 1 12 9 2 (1 .5 3% )

11Refractories f o r Industrial Processing

As shown in Table 6, a 2% im provement in boi ler efficiency leads to a 2.3% im p r ovement in fuel cost and consum ption, while the 10% improvem e nt in the efficiency of the transfer pipework insulation leads to a 1.9% i m provement in fuel cost and consum ption. As shown i nthe tables, there are also decrea ses in e m i ssions as sociated with im prove ments in boiler efficiency and pipework ins u lation. If these fuel savings are thenapplied to the che m ic al, petroleu m refining, and pul p and paper industri es, estimates can be m a de concerning th e possible energy savin gs resulting from i mple m entation of these im prove ments in each industry . Table 8 shows the res u lts of such an analy s is.

Table 8. P o tential ener gy s a vings fr om improved boiler efficiency due to improved r e frac tories and i m pr ove d tr ansf er pi pe - w ork i n sul a ti o n
Capture Projec ted IOF ind u str y segmen t TBtu % basis fuels avi n g s (% ) (TBtu) Chemic a l industr ys t eam oppor t uni ties Prese n t u s age of f

u el f o r

ge n e rat i n g st eam 1, 54 0 Op p o rt uni tyf o r i m provi ng b o i l e r effi ci ency 2. 3 fr om 85 t o 8 7 % F u el save d 35 Op p o rt uni tyf o r re d u ced l i n e heat l o sse s by 10 % 1. 9 F u el save d 30 C

h emi c al i n du st ry f u el re duct i on 65 40 26 Pulp and pap er ste a m op portunities Prese n t u s age of f

u el f o r

ge n e rat i n g st eam 2, 59 6 Op p o rt uni tyf o r i m provi ng b o i l e r effi ci ency 2. 3 fr om 85 t o 8 7 % F u el save d 60 Op p o rt unityf o r re d u ced line heat l o sse s by10 % 1. 9 F u el save d 49

Pul p a n d pa pe r i n dust r y

f

u el red u ct i on 10 9 40 44 Petroc hemicalste a m oppor t unities Prese n t u s age of f

u el f o r

ge n e rat i n g st eam 1, 67 5 Op p o rt uni tyf o r i m provi ng b o i l e r effi ci ency 2. 3 fr om 85 t o 8 7 % F u el save d 39 Op p o rt uni tyf o r re d u ced l i n e heat l o sse s by 10 % 1. 9 F u el save d 31

Pet roche mi cal i n d u st ry f u el re duct i o n 70 40 28 T o t a lste a m o ppor t uni ty 24 4 40 98

According to the DOE-EE RE Best Pra c tices report c oncerning stea m usage in the che m ic al manufacturing, pul p and p a per, and petroleum industries, 4 154 0, 2 5 96, and 167 5 TBtu of fuel, respectively , is used to generate st ea m p e r y ear by each industry (see Table 8). As can be seen, on a 40% capture basis (i.e., 40% of the existi ng plants w ill use the improved refractor y and insulation s y s t e m s), the lev e ls of projected fuel savings are 26, 44, and 28 TBtu, respectively , for the chem ical, pulp an d pap e r, and petrol eu m refining industries. Th is results in a total projected fuel savings o f 98 TBtu across the three industries.

12Refractories f o r Industrial Processing

4.3.4 Barrier s Rel a ted to Refr actory and I n sulating Materials for Boilers and Reactors The central conclusion from th ese analy ses is that decreased fuel co nsum ption resulting from i m proved boiler efficiency can be achieved thro ugh be tter insulation practices. A s shown, the i m pact of increasing boiler efficiency by 2% and reducing heat losses during steam tr ansfer by 10% will result in a total fuel savings of 98 TBtu for th e industries studied. Addr essing the following barriers as sociat ed with the perform anc e of refractory and insulatin g materials used in boilers and reactors would reduce energy requirements: 1. Unavailability of insulati ng refractories with su fficiently low thermal conductivit ies to lead to increase s in energy efficiency levels for boiler operations. 2. Unavailability of im proved insulating materi als fo r transfer pipework that could help reduc e heat losses during stea m tran sfer operations.


## 4.4 Gasifiers
Gasifiers are currently bein g used in th e chem ical and petrochem i cal industr y f o r coal and biom ass gasification and inthe forest pro ducts industr y specifically for black liq uor gasification. This technolo g y has the p o t e ntial for bio m ass solidfuels to be conv erted into fue l gas “sy ngas ” consisting largely of hydro g en (H 2 ) and carbon m onoxide (CO). This gas can then be burned cleanly and e fficiently in a gas turbine to generate ele c tricity and/or used to s y nthesize cl ean transportation fuels or chemical s. Gasification is currently used in the che m ical industry as a m e ans to pro duce clean energy , h i ghvalue energy products, and various petrochem i ca ls fro m coal (including th e possi bility of producin g hy drogen fuel, h i gh-grade transportati on f u els, and indus trial-grade methanol). Experimental gasifiers ar e being applied in a few chemical and pulp and paper p l ants for coal or black liquor c onversion, wh ile gasificati on is also bei ng used as a means of using biom ass as an energy so urce rather than a waste product. In th e fut ure, the forest pr oducts ind u stry m ay use gasification to replace Tomlinson boile rs.
A li m itation on the use of these experi mental gasi fiers is the lack of reliable refra ctories for containment. If the refracto ry requirement could be met, coal, black liquor, and biomass gasification could lead to greater reducti ons in purchased energy and evenchange these industries from net energ y im porters to net energ y exporters. 5 G asification holds the prom ise of generating 175% m o re electrical power than do cur r ent technolo g ies, but the gasification technolog y currently in use requires fr equent refract or y re lines of the vessels, hence reducing the econom i c and energy benefits. 5 Addi tionall y , although chem ical or pul p and paper m anufacturing faciliti es are not currently used to produce transportation fu els from bio m a ss, the y m ay become a valuable asset for est ab lishing an infrastructure f o r su ch technology. Future gasification-based “biorefineries” m i ght prod uce a variety of re newable fuels, electric ity, and chemicals in conjunctionwith pulp an d paper prod ucts.
4.4.1 Industrial Applications of Process Technology Chem ical and petrochem i cal — coal and biom ass gasification Forest produc ts — black liquor gasification
4.4.2 Current Tec hnology A coal gasifier generally consists of a m e tallic shell protected by a l i ning m a de up of two t o six concentric lay e rs of refractory protecting the interi or of the vessel. Coal gasifers are expected t o

13Refractories f o r Industrial Processing

operate at high tem p er ature s and m odera te pressur es, and with gas and particle flows containing H 2 , CO, H 2 O, C, H 2 S, HCl, hy drocarbons, m e tallic i mpurities, and s a lts. These linings have average lifeti m es on the order of 7000 run h ours and generally fail because of ex cessive mechanic al w ear (erosion), che m ic al penetration of slag into the structure of the innerm ost brick (corrosion), or some co m b i n ation of these two m echan is m s . Erosive wear occurs as the feedsto c k itself causes phy s ical decay of refractory hot-f ace surfaces when injected at high velocities. Corrosive attack occurs w h en th e coal slag residues penetrate the r e fractory hot face surfa ce, thus weakening the refractory by form ing solid-solution phases.
The nom inal scale of an av erage pulp and paper m ill i s 6 m illion lb/d of black liquor solids (BLS)—the equivalent of 1.5 m illion Btu/h or 438 M Wfuel—corresponding to 1900 m a chine dry short tons per day of pape r productio n (1 725 m e tric to ns). 5 Pulp m i l l s processing m o r e than 6 m illion lb/day BLS account for about one-third of all U.S. capaci ty today , and this fraction will grow over ti me as m ill co nsolidations c ontinue. A standard sized gasifier for this size mill is considered. This unit was assu m e d to have a BLS concentration of 80% and a stea m pres sure of 1870 psia.
4.4.3 Energy Im pact For the following analy s is, we considered a co m b ined -cy c le gasifier typical of those used for coal or black liqu o r gasification with the requi rem e nts above. Co m b ined-cy c le black li quor gasification has the potential of prod ucing m o re th an twice the curr ent output of electricity per ton. 5 In m any cases, power in excess of a chem i cal or pulp m ill’ s needs could be produced and exported. Fur ther, if gasified coal or black liq u o r were converted to a high-q u ality sy nthetic gas sim ilar to sy n g as produced from fossil residual o il, the energy and e c onom ic benefits would be even greater. Conventional processes could then be us ed to convert the gas to liquid fuels or hy dr og en
. According to the econom ic and energ y an aly s is perfor m ed by Larso net al., 5 f u ll i m pl ementation of the black li quor gasification init iative could achieve the followin g energ y ben e fits by 202 0:
1. Productionof up to 8 GW of electricity from sustainable, renewable raw materials b y 20 20 throug h black liquor gasification alone. 2. Productionof 16 GW or m o re of electric power for th e application of black liqu o r gasification in conjun ctionwith wood re sidual gasification b y 202 0

. 3. Alternatively , displacem e nt of m o re than282 m illion barrels of oil per y ear if the se technologies were applied to s y ngas pro duction t o be used for liqui d fuels.
The total of these biomass energy sources consumed at pulp m ills in 2002 was esti m ated at 1.6 q u ads (on e quad is 10 15 Btu). 6 T h e p o tential renewable energy generation p o tential from black liquor i nthe pulp and paper industr y in the s outheastern United States is shownin Table 9.
Refractories and insulatio n materials play ke y rol es inmany of the unit o p eration s involved in both of these industries. It i s esti m ated that pr ocesses affected by ref r actories acco unt for about 40% of the industries’ dire ct energy consu m p tion. Based on subsequent analy ses of typical furnaces and unit processe s, i m prove m e nt of refractory sy stem s for these two industries could lead to energy savings opport unities up t o 12 9 TBtu/ y ear.

14Refractories f o r Industrial Processing

Ta ble 9
. Renewa ble energ yg e nera ti o n potenti a l (billio n kWh/ y e a r ) fro m bl a c k liquor in the p u lp and paperindus try in th e sou t he as tern United S t ates

Technol o gy Po t e nt i a l by 20 20 (billio n kWh/ y e a r ) Eq u i v a l en tene r g y (T B t u/ye ar )

C o nv e n t i onal c o al com bust i o n 72 6 (33–35% e ffici ent) (ene rgynee d ed ) Com b ined cycle gasification 66 0 (45–50% e ffici ent) (ene rgynee d ed ) To ta l i m pro v emen t 6 6 Chemic a l 44 0

Fores t pr od uc ts Tom l i n son rec ove ryboi l e r 4. 4 15 Hig h -e fficienc yTom linson 16 .7 57 recovery boiler Com b ined cycle gasi fi cat i o n 36 .2 12 4 To ta l i m pro v emen t 6 7

4.4.4 Barrier s Rel a ted to Refr actory Materials for Gas i fiers Addressing the following barriers as soc i ated with th e performance of refractory materi als use din gasifiers wou l d reduce energy requirements:
1. Unavailability of advanced refractory materi al s withim proved corrosion/erosi on resistance, i m proved reliability , and re duced maintenance costs. 2. Lack of refra ctories with resistanc e to high alkali atmospheres and high levels of stress, which lead to gasifier contain m ent issue s
. 3. Lack of alternate refractory designs which w ould provide refractory surfaces (us i ng coatings, che m ic al alte ration of refractory surfaces, phy s ical alteration of refractory surfaces, etc.) that
are m o re i m p e rvious to wear and corrosive attack. 4. Unavailability of refractory m at e rials with greater therm a l co m p ati b ility with m e tallic materi als use din gasifiers.



## 5. Overall R&D B a rri ers and Pa thwa ys fo r Re fra c tor i e s
Evaluation of refractory us age, barriers, and needs of these sever al e n ergy -intensive process industries sho w s that several co mm on them es arise in the pursuit of im proving ref r actory materi als for greater energ yefficiency

. These the m e s relate to i m proving energy efficiency by reducing energy loss and i n creasing productivity thr o ugh the development of higher-strength refractories capable of ope rating at high er tem p er atures, the development of refractories with lower therm a l conductivity to reduce wall losses athigher service tem p eratures, th e tailoring of therm a l expansion capabilities of current refractor ies, and the devel opm ent of refractories with greater resi stan ce to che m ic al and mechan ical w ear ( c orrosion, eros ion, abrasion, etc.). This concept is shown in Fig

. 2

.

15Refractories f o r Industrial Processing

Fig. 2. Improving refractory materials for improved energy eff i ciency.
Through analy s is of current refractory use, current barriers, possible i m prove m e nts in process energy efficiency , and R&D refractory needs fo r several process i ndustries, many issues common to m u ltiple industries become apparent. The r esear ch focus areas and technical R&D topics below have been identified as issues co mm on t o m any applications of refractories.
1. Understand t h e degradati o n mechanisms of refractories in different environments Determine the m e chanisms responsible for th e chem ical and m ech anical degradation of refractories in the various envir onm ents in which the y operate.
2. Achieve impr ovements in thermal control Determ ine the therm o m e c h anical properties of re fractor y m aterials and develop materials that will allow furnaces to operate with longer cam p ai gns and with higher levels of insulation to reduce heat losses. This may also involve the im ple m entati on of new furnace designs, the form ulation of newly redesigned process es, or the re-e ngineering of existing industrial practices.
3. Evaluate thermomechanical properties at elevated temperature Determine the key properti es of refracto r ies at elevated tem p eratures, includin g h o t m odulus of rupture, hot crushing str e ngth, creep be havior, refractoriness under load, physical and therm a l spall resistance, dimensional chang es (elastic m odulus, therm a l expansion, and growth from chem ical alteration), and th erm a l conductivity
. 4. Form an expert advisory committee Assemble a committee com posed of current and retired industr y e xperts to serve in an advisor y role for industr y - f o cused refractor y R&D projects. Additionall y , i nvent or y and preserve exist i ng industrial equipm ent an d fac ility resources through sy stem ati c surve y s of refractory experts (especi a lly retirees) s o that industrial furnaces an d existing laboratories can be utilized, when possible, to augm ent new experi mental sy stem requirements.

16Refractories f o r Industrial Processing


## 6. Specific R&D Areas with Barriers and Pathways

The following text summarizes pathway s for overc oming barriers for the six spe c ific R&D ar eas that can y i eld the greatest r e turns in refractories.


## 6.1 Improved Castable and Monolithic Refractory

Barrier Inadequate resistance to co rrosive and mechani cal w e ar, which lim i t s the use of castable and
m onolithic refractories. Pathways

• Fabricate fusi on-cast refrac t ories (such as alu m ina zir c onia refracto r ies) that do not include silica or other glass form er s. These refractor ies should possess great er corrosion resistance and therm o el astic properties. The refractories would be of use to i ndustries such as glass, pulp an d pap e r, and many others.

• Fabricate co m ponents for continuous measurementof param e t e rs such as tem p erature, bath chem istry , etc., that will have long-term stability in hi gh-tem p erature industrial solvents, such as cry o lite for the electroly t i c production of alum inu m . Candidate materials su ch as HfB 2 , HfC, ZrB 2 , ZrC, and TaC should be cons idered.

• Develop oxide/nitride grain boundar y a dditives lead ing to closure of open poros ity in silica,
m

u llite, and magnesiu m alum inates as u sed by the gla ss and other i ndustries.


## 6.2 Modified Fiber Materials

Barrier Lack of fiber insulation m a terials with lo wer thermal conductiv ity , g r eater chemical resistanc e , and higher te m p erature stabili ty lim its. Pathways

• Produce froth ed latex/fiber mixes for gunning t o reduc e airborne fib e rs during ins t allation. Enhance adhesion of m ateri als to steel an d other m e tal s for application in heat treatm e nt furnaces. Dev e lop new inorganic binder sy stems.

• Fabricate fibrous m at e rials with greater strength and l o wer friability for use in heat treatm e nt and chem ical and petrochemical industries.


## 6.3 Surface Modification (Coatings, Physi c al or Thermal Alteration)

Barrier Lack of techniques and m at e rials for apply i ng surface coatings or inducing phy s ic al alteration of refractory surfaces through either m e chanical or therm a l means.

17Refractories f o r Industrial Processing

Pathways

• Modify surfa ces or near-su rfaces of sintered alu m ina and m u llite refractories by apply i ng corrosion/erosion-resistant coatings such as spinel phases (or additi onal corrosion-resistant materi als) for use by industries such as g l ass, pulp, and paper.

• Determine the effect s of “preexisting” refr actory heating conditions that, when applied concurrentl y with high-i n t e nsity i n frared heating, m odifies the surface of bonded refractories and results in the residual com p re ssion of a m odified surface at s e rvice te m p er atures. One advantage of this could be an increase inthe “strain-free” temperatu r e of refractor ies used in process industries.

• Determine the applicability of radiation-heati ng attenuation/m itigation, and if applicable, si m u late refr a c tory structures that would maxi m i z e its effect to optimize r a diant heat transfer (e.g., im prove ox y -fuel fir e d sy stem s fo r the alum inu m , glass, metal casting, and iron an d steel industries).

• Investigate the effect s of radiative heating and transm i ttance in refra ctories on therm a l conduction for m i ni mizing therm a l losses fro m various types of fur n aces used throughout th e select ed industrial are as.


## 6.4 Synthetic Aggregates and Pow d ers
Barrier Lack of highe r-perform ance aggregates th at would inc r ease the life and durability of refractory pro ducts used across the various industries and lack of hi gher-quality matrix materi als thatwould increase the durability of refractories. Pathways

• Measure and m odel str e ngth as a function of aggr egate size distribution. Tailor m i crostructure so that flexure and com p re ssion strengths are incre ase d.

• Explore candi date aggregate coatings as “add itives” that control or binder grain boundar y effects ( e .g., diffusion, heat transfer, corro sion-resistan ce, etc.) for im proved refr actory processing.


## 6.5 High-Temperature Properties of Refractories

Barrier Lack of infor m ation on the high-tem p erature therm o mechanical andcorrosion properties of current and n e wly develop e d refractory materials. Pathways

• Develop realistic test methods a nd envir onm ental tests sy stems inorder to evalu ate elevated te m p erature p r operties. Evaluate corrosion behavior of refractories for various effects of water/CO/CO 2 /alkali conte n t on th e corrosion and pha se stability of refractories u sed in gasifiers and in the glass, alum inu m , steel, and m e t a l casting industr ies. Develop lab-scale sy stems to evaluate the degradation of re fractories up to 2000°C.

• Sy stem atic all ycharacteriz e and m odel re heat-generate dpermanent expansion effects in fusion-cast and bonded refractories, a phenom enon known to occur in m any refractory sy stems used throughout the various process industries, but not curr ently understood.

18Refractories f o r Industrial Processing

• Perform postm ortem analy s is on failed refract ory components from several industries and identif y servi ce-li m iting flaw types. Use com ponent sam p les for measurement of strength distribution and com p are t o strength dis tributio n of vi rgin m ateri als. Perform pro b abilistic strength-size-scaling analysis using bothdistri butio ns as input and p r edict failure time of
co m ponents.

• Measure the corrosion resistance of bonded refractories as a functi on of refractory sintering te m p erature and interpret the performance in referenc e to service te m p erature.

• Investigate the effect of sp eci men size i nrefractories by m e a s uring strength (m o dulus of rupture) as a function of speci men size i nbonded or fusion-cast ref r actories. D e term ine if variations in strength can be represente d by a Weibull distribution and if strength is sizescaled.


## 6.6 In Situ and Graded Refractories
In situ refractories are defi ned as brick or uns haped pr oducts that react internally or with furnace at m o spheres and/or slag co m ponents to enhance their performance. Natural in situ formation of Fe-Mg-O spinels in steel- m aking furnaces perm its i m proved life and durability of these furnaces.
Barrier Lack of R&D to im prove existing in situ re fractory s y stems and for developm ent of new in situ s y stems for additional industrial applications Pathways

• Model crack initiation and growth as a function of m a terial, depth, and service properties using m i crostr ucture-basedfinite ele m en t analy s is (e.g., μ- FEA, OOF). Sim u late and optim ize hypothetical m i cr ostructures that hinder crack growth.

• Develop high -intensity infr ared heating techni ques to fabricate optimized gradedrefractory structures, and m e asure therm o m e chanic al stability and corrosion re sistance.

• Model, sim u late, and design refractory micros tructur es that prom o t e m a xi m u m creep and erosion resistances.

• Determ ine the effect of cry s tallography of base and in situ phases on the development of therm a l stresses and the stability of in sit ulay e rs.

• Determ ine an d optim ize “ s ubstrate” surf ace geo m etrie s (e.g., dim p les, corrugate d, saw-tooth) that will m i ni mize shear str esses in therm o - e nvir onmental barrier refractory coatings that are subjected to a thermal gradient.


## 6.7 Sensors for Materials Performance

Barrier Lack of sensors to m onitor refractory -related issues in cluding wall thickness regression, gas phases, and other environmental conditions. Pathways

• Develop sens o rs and m e th ods for the m easure ment of spectral e m i ssivity for application in glass tanks and m e t a l m e lti ng furnaces.

• Develop sensors and m e th ods for the m onitorin g of wall regression due to corro sion, erosion, and wear in glass tanks and metal melting furnaces.

19Refractories f o r Industrial Processing

• Develop continuous real-ti m e measur e ment technique s for param e t e rs such as tem p erature, pressure, m e l t analy s is, flue gas an aly s is, and environmental gas phases.
The tasks and the industrie s which will benefit from th e projects described above are shown in Table 10. As is evident from the t a ble, these s uggested R&D pathway s are crosscutting. Although there is a curr ent trend for many of th ese industries m oving overseas, it is believed that the R & D pathway s proposed will dir ectly benefit U.S. industr y
. Even as processes such as alu m inum
sm elting and glass producti on m ove off shore, ther e will still be a need for remelti ng and other productio n d o m estically

.

Table 10. Rec o mmended R&D pathways for advance d refrac t ories

Tech n i calR&D pote ntial path w a y s Aluminum Cement & lim e Chem. / pe tr och emica l Ind u str y se gment
Fores t pr oduc ts Glass Heat treat m en t Iron & s t eel Metal cas t in g Improved castab l e and m onolith ic refractories X X X X X X X X

Modified f i ber
ma t e ri al s X X X

S urface m odif i cations (coatings,
a l te ra ti ons) X X X X X X

S y nthetic aggr egates and powders X X X X X X X

Elev ated t e m p erature refractor y properties X X X X X X X

In situ and gr adient refractories X X X X X X X

Sensors for materials performance X X X X X X X X

2021Refractories f o r Industrial Processing



## 7. Ref e ren ces

1. J. Mosser and G. Karhut, “Refractories at the Turn of the Millennium , ” Paper presented at UNITECR ’99, Berlin, Germany , p p . x x v–xx x, Sept. 1999

. 2. D. W. Freitag and D. W. Ri cherson, Opportunities for Advanced C eramics to Meet the Needs of the Industries of the Future, DOE/ORO 2076, U.S. Department of Energ y , Of fice of Industrial Technolo g ies, Decem b er 1998. 3. U.S. Department of Energ y , Energ y Inf o rm ation Ad ministration, 1 9 98 M E CS Consumption, Table N3.2, F u el Consum p tion, 1 998

. 4. U.S. Depart ment of Energy, Office of Energy Efficiency and Renewable Energy, Steam System Opportunity Assessment for the Pulp and Paper, Chemical Manufacturing, and Petroleum Refining I ndustr ies: M a in Report, available online at htt p ://www.oit.doe.gov/ bestpractices/technical_publications.s html under “Market Assessments.” 5. E. D. Larson, S. Consonni, and R. E. Katofsk y , A Cos t-Benefit Assessment of Biomass Gasification Power Generation i n the P u lp and Paper Industry, Princeton University , October 2003. Available online at http:/ /www.pr incet on.edu/~ener g y / pub lications/pdf/2003/ BLGCC_FINAL_REPORT_8_OCT_2 003. pdf. 6. DOE/EIA Renewable Energy Annu al 20 01, DOE/EIA-0603, 20 01

2223

# APPENDI CES

2425Appendix A — Chemical and Petrochemical



## Appendix A: Discussion of Refractory Usage by Process Industries

A.1 Aluminum

Current Ind u stry Ope r ations and Refractory Use Alu m inum productionis energ y -intensi ve, consum in g about 0.4 q u ads of electrical energy p e r y ear in the United States. 1 Additionall y , the industr y f aces many of the sam e co mpetitive pressures as th e steel industry, including global com p etition, energy consum ption issues, and polluti on abat em ent. Therefore, a technology r o ad m ap has been created to address these issu es by targeting ar eas such a s e n ergy consum ption, productivity , em is sions , recy cling, quality , alternate tech nologies, and by -products. 2 Many s y stems are used in the producti onof alum inu mand its allo y s , all of which depend onth e proper selecti on and m ana ge m e nt to ensure the cost effectiveness o f the metallur g ical and refractory pra c tices. These sy stems include stea m boil e rs for Bay e r plants, calciners, and carbon baking f urnaces used for the production of the anodes which are co nsumed in the Hall-Heroult reduction process. In Hall- Heroult electr o ly tic reduc tion cells, the key refractories are those us ed to support the cathode hearth and to m i n i m i ze the pen e tration of bath constituent s into the carbon cathode and underl y i ng refractories. Melt ing furnaces for alloy pr oduction by the primary and secondary pr oducers include large fossil-fuel-fire d reverberatory f urnaces as well as a variety of induction fur n ace designs dom inated by the co reless and the channel induction types. Te m p erature s and corrodant che m istrie s, as well a s furnace at m o spheres, determ i n e the lining used for each of these processes. The ref r actories usedfor each will be briefly reviewed. Primary Alu m inum Prod uction The producti on of prim ary alum inu m metal is based on three m a jo r steps. The first involves th e mining of ba u x ite ore. Ther e are no high-grade deposits in the United States; therefore, refractories play little role in this process. The second process involves the conversion of b auxite to metallurgical grade a lumina . The Bay e r process is bas e d on digestion of bauxite in caustic solution heated with superheated stea m to f o rm sodium alu m i n ate. I m purities are r e m ove d from the pregnant caustic by chem i cal reactions with dissolved species (pri marily SiO 2 ) and f i ltration of i n soluble im purities (prim arily iron oxide). The saturatedsolution is then cooled in precip itator tanks in which alu m inum tri hy drate is precipitated and then recovered by filtration. The al um inum trihy drate is converted to alum ina by calcination. Two methods of calcination are em ploy ed in the i ndus try : use of flu i d bed calciners and use of rot ary ki lns. The third pr ocess involves conversion of alum ina to al um inu m by electrolytic reduction usin g th e Hall-Heroult process. In the reduction process alu m in a is dissolved in a m o lten bath (cry olite, Na 3 AlF 6 , with additions of AlF 3 , CaF 2 , and som e times LiF and Mg F 2 ). The cell for this process utilizes a contain m ent sy stem consisting of a steel shel l lined with a castable r e fractory , a porous insulating ref r actory , a less porous sem i- insulati ng ref r actory , and f i nall y firebrick. A carbon cathode acts as the bottom of the cell fo r m o lten alu m inum containment. The side-wall refractorie s ar e generally phosphate-bonded alum ina brick or alumina castable materi als. Be cause the sides of cell have less i n sulation, m o re heat is lost through the w a lls than the floor. The lower

26Appendix A — Chemical and Petrochemical

wall te m p er ature is actuall y beneficial, causing el ectrol y tes in cont act with the wall to solidif y and form a “f rozen ledge” which protects the walls of the cell fro m penetration by m o lten cry o lite. T h is practice is su ccessful, but i nvolv es a trade-off between energy efficiency and electroly tic cell stability and lifetim es in terms of energy consumption. Reduction cells currently e m ploy variou s refract ories just below th e carbon cathode which during service degrade in various way s , perm itting bath constituents to m ove into th e cathode carbon and refractorie s. The sy stem s i nplace today include fireclay bricks, castable refracto r ies, se miinsulating ref r actories, and insulating bri c ks. Sy stem s for prim ary alum inu m production involv e several different designs d e pending on th e level of am p e rage and the num be rs and array of anode blocks. The current intensity for o p erating reduction c e lls through o u t the world r anges fro m 60,000 to 500,000 A. Yet, th ey all still invol ve a carbon cathode hearth and consumed carbon anodes in which the bauxite ore charge and the s y stems of alkali fluoride fluxes are placed and held while the reduction pr ocess is carri ed out conti nuousl y . T ypic a lly th e reduction pr ocess i s carried out at a tem p erature in the range of 960 to 970 ° C. The refractories are key com ponents in reduction cells. The at m o sphere inside the cavity of a reduction cell is very reactive, containing a mixture of CO 2 , CO, HF, SO 2 , and part iculate fluoride salts.
In all cases it seems that the form ation of a feld spathic co m position at the interface between the cathode and th e barrier is highl y desirable but that other bath species can still penetrate the barrier and lead to hi ghl y sh ortened cell life. Furthe r, downward m ovem e n t of alkalis and bath constituents through the he arth toward the subhearth insulation eve n tuall y result s in the failur e of the furnace, an event which is still quite unpredic tabl e. Because of this, furnace lives vary fr om hundreds to thousands of d ay s
. Taberaux 3 ha s reviewed the failure m e c h anis m s of al um inu m redu ction cell sy ste m s. Fire clay brick in one reported case l asted over 3000 day s , showing that the materi al itself can m eet the challenge, all other factors being o p tim al in their selection and control. Castables have disadvantages in cast-in-place sy stems, and current l y the preference is for precast m onolithic sy stems, which have had good success. Two types of dr y barrier refractories ar e currently being used. Their advantages res t on ease and rapidity of installation and lack of joints . The y include alu m inosilicates on the one hand and anorthite fe ldspar on other, chosen because itundergoes beneficial in situ reactions and is, in fact, patented.
Carbon a nod e baking furn aces have historically been constr ucted of alum inosilicate bricks. These bricks have sufficie n t refractoriness that e ffort s to replace the m with alu m ina-reinforce d versions have not been cost-effective. The cha llenge to the brick co mes fro m its coking an d fr om the alkalis present in the electrode feedst ock. Most recently, fireclays with very low alkali content have been used for the production of bricks increasin g ly designed with surface l o cking s y ste m s that reduce the bowing of walls, which is the principal reason for th e replacement of the refractories. Because such large num ber s of br icks are used in carbon baki ng fur n aces, attemp ts have been ma de to recy cle the m , but past effort s have not resulted i nthe formulation of a costeffective protocol.
Schubert 4 recently addressed the basic issues of m ove m e nt of the flue walls, and points to the findings i np o s tm ortems that the insulation m ay be in adequate for the support r o l e that it play s. The many challenges to the flue walls i n clude (1) alkali infiltration and attack from bath carry over, via recy cled anode butts in the recipe ; (2) fluoride salt attack fro m bath carry over, via recy cled anode butts in the recipe; (3) m i nor “squatting” from el evated tem p eratu r es and load; (4) mechanical dam a ge fro m impact of the anode and/ or the crane during l o ading and unl oadin g ; (5) thermal shock, especially duri ng th e cooling c y cle; (6) construction details that aggravate

27Appendix A — Chemical and Petrochemical

norm a l w ear and tear; (7) various proble m s due to im proper expansion a llowances; and (8) coke sticking to refractory , aggravated by alka li content. Semifabricated and Secondary Aluminum Production Secondary al um inu m production involv es re cycling of aluminum m e tal scrap . This is carried o u t in a variety of furnace desi gns. When large volum es o f alloy are required, reverberatory furnaces are traditionally used. Thes e furnaces ha ve seen a constantly evolving refractory practice. Monolithics replaced bricks in the distant past, and currently m onolithics in the f o rm of precast “big blocks” are receiving renewed interest. A recent paper b y Can o n 5 reports that the real advantage of precast furnace co m ponents rests in th e ti m e savings r ather than in th e extension of service life.
As in the case of the subhearth refractories usedin pot furnaces, it is essential to develop a freeze zone in the walls of all the furnaces. This is done by s e lection of refractories andappropriate thicknesses. I t is also essen tial to restrict the penetr ation of the alum inum alloy into the refractory , which is achieved by incor poration of additiv es, some of which are proprietary. As it is im possible to keep ox ygen from reacting with the aluminum met a l, a so-called bellyband develops in all types of m e l t ers. Bec ause of the fluctuating level of th e metal in some furnaces, the bellyb and can be quite wide and eventually ex tend into the furnace to such an extent that it
m

u st be re m o ved. In the case of the largest reverberat ory types of furnaces the re m oval is
so m e ti mes carried out using large roboti c devices. In many instanc es the furnace has to be shut down to effect adequate rem oval. In the hearth region of the m e lter, linings of sili con nitride– bonded silicon carbide are used for m o lten alum inu m contact areas.
After melting, the m o lten alum inu m flo w s through re fractory

- lined troug hs between the various process steps. These troughs are typically lined with oxide ceram i c s such as fused silica or m u llite with 10–15% porosity and special additives to resist wetting. Th ese m aterials ar e installed in board or castable form and are used due to thei r low therm a l expan s ion and good therm a l shock resistance. Still, erosion and abrasion issues are of concern. SiC-based material s have been considered for this application but are more expensive than oxi de refractories. Bellyband buildup is th e overriding issu e in melting furnaces. Quesnel et al. 6 have reviewed the problem for a l um inu m holding furnaces and m e lt ers. There is a lac k of understanding concerning the mechanisms of belly band form ation. The two type s of tests typically used in the study of candidate refractories are a bellyband cor r osion test (which is a si m p le cup test) and an imm e rsion test (which really looks at the penetr ability of the refractory by th e metal). Long use of these tests has produced inconclusive answers about th e mechanism of att ach ment, and it is apparent that new approaches are ne eded.
Barrier s Refractories play ke y role s in m o st of the unit o p erations inv o lved in the pr oduc tion of prim ary and secondary alum inu m
. It is estim ated that about 9 0 % of the dir ect energy us e by the in dus try is in processes a ffected by refractories. Re c o mmended im prove ments for refractories include applications for refining, re duction, carbon anode baking, and m e lti ng operations. Based on subsequent analy ses of typical furnaces and unit proc esse s, i m prove m e nt of refr actory s y stems for the alum inum industry could lead to ener gy savings opport unitie s up to 29.2 T B tu/ y ear. The specific barri ers are as follows:

28Appendix A — Chemical and Petrochemical

• Aluminum Refining Unavailability of im proved refractories fo r superheated steam gen e ration, as well as im proved refractories for calcini ng oper ations, particularly rotar y kilns for alum ina and lime, which could l ead to im proved energy efficiency for ref i ning operatio ns.

• Aluminum Reduction Lack of unde rstanding concerning the mechanisms an d degradation scenarios leading t o the failure of reduction cell refractories and, ultim at el y , th e reduction cell. Further, th ere is a lack of im proved linings and ref r actories with im prove d resistance to bath penetration that would perm it extended lives for reduction cells.

• Carbon Anode Baking Fur naces Unavailability of stronger insulating sh a p es for com p onents of carbon baking f urnaces.

• Aluminum M e lting Furnac es Lack of unde rstanding reg arding the m e chanism s of bellyban db u il dup form ation. This is
co m p licated by the inability of current tests to provid e conclusive answers regarding th e mechanism of attach m e nt and to pr ovid e sufficient perform ance projections.
R&D Pathw ays

• Refining

o Develop im proved refractory an d insulat i on s y stems f o r high-tem p e rature ste a m generation.

o Im prove refractory m aterials for calcining ope rations, particularly f o r rotar y kil n s.

• Reduction

o Develop a fuller understanding of cell refr actory failur e throug h chemical and phy s ical m o d e ling of the re actions and transport m e ch anism s . Develop k nowledg e and control of all aspects o f the che m ica l and phy s ical properties of the refractori es, and optim ize drefractory design approach es for reduction cells carry ing increasi ng current intensities.

o Develop a sidewall refracto ry design that woul d allow direct contact with the m o l t en cry o lite bath, perm itting elimination of th e “frozen ledge.”

o Develop refra ctories with im proved toughness, i m pactresistanc e , and abrasion resistance for the hearth region of reduc tion cells.

• Carbon Baki ng

o Develop unde rstanding of th e manner in which insulation com ponents are being affect ed chemically and mechanic ally bythe loads f r om the overly i ng charge and wall refra ctories. Perform s tudies of the mechanic al properties of such used refractorie s to provide answers to th ese and related questions tied to assuring therm o m e chanical stability.

o Develop im pr oved refractories and furnace d esigns for reducing ene r gy consum ption in carbon m e l ting fur n aces though m odeling of design, process control, quality control, and selection of hot-face refr act ories, not only in the flue walls but in other
co m ponents of the furnaces.

29Appendix A — Chemical and Petrochemical

• Melting Furnaces

o Develop m o r e accurat e si m u l ations of the melting process.

o Develop a m a terials approach that involv es the development of graded m onolithic linings, cast in place or precast, which have m u ch denser surfac e re gions and m i ght also contain additives to di ssuade penetrants . Determi n e the ke y factors which affect penetration and attachment such as the perm eability of the surface region to the metal or altered m e t a l.

o Develop im proved refractories for alu m inum melting and casting o p erations, including advanced refra ctories for reve rberatory m e l ting furnaces and prefired refractory riser tubes for low-pressure al um inu m die c asting applications that are
econom ical, strong, th ermal-shock-resistant, and nonwetting to m o lten alum inu m , and that have low gas permeability

.
o Develop efficient, long-life degassing co m ponents for alu m inum alloy production.



## A.2 Cement and Lime

Current Ind u stry Ope r ations and Refractory Use The United States is the third largest cement-pr oducing countr y in the world (after China and India). The pr oductionof c e m e nt and its interm ediate product, cement clinker, h as risen steadily over the last decade, with consum ption incr easing 40% while production has only increased 27%. This has led to increased im ports in the short term , mainly from Canada and Mexico, but could lead to furthe r expansion o f the dom estic industr y inth e long term . Currently, the r e are 115 cement m anufacturing plants in the Unit ed States, with about 75% of the total pl ants owned b y only 10 large co m p anies: L a farge North A m eri ca, Inc. ; Holci m (US ) , Inc.; CEMEX, SA de CV; Lehigh Cement Com p any ; Ash Grove Cem e nt Co m p an y ; Essroc Cement Corporation; Lo ne St ar Industries, In c.; RC Cement Com p any ; Texas I ndustries, Inc. (TXI); and California Portland Cement Co mpany
. The 199 7 Econom ic Census report (sam pling 279 e s ta blish m ents) shows that refractories (clay or non-clay ) account f o r 2.5% of the total c o st for the cement industr y, or approximately $61.5 million of the total $2.5 bil lion spent. A typical m odern cem e nt plant m ay include the following refractory lined units: (1) a preheater equipped with several cy clones as a heatexchanger, (2) a precalciner with a burner for the decarbonization process, (3) a kiln, and (4) a kilncool er. The preheater, cy clones, and heat exchangers heat the ce men t raw m e al or slurry befo re it is passed to the rotary kiln. This aids fuel
economy by decreasing the am ount of heat that the kiln m u st supply. The precalciner uses preheated com bustion air from the clin ker cooler and/or kiln exit gases with se parate burners to calcinate up to 95% of the raw material. A precalcine r kiln s y stem c onsisting of a rotary kiln with an external furnace may also be used for heating ce m e nt raw m eal t o calcination te m p erature s
. This sy stem also often has a m u ltistage cy clonic preheater attached to it for f urther heating efficiency

. The kiln is wh ere ce ment raw m i x is dried, calci ned, and burned into clinker at t e m p eratures of 2600 –30 00°F

. Kilns can be rotary (rotati ng at one t o th ree revolutio ns per m i nute) or shaft type and use coal, oil, gas, or other fuel for heating. A rotary kiln will generally be di vided int o zones

30Appendix A — Chemical and Petrochemical

for dr y i n g , pr eheating, calcining, burn i n g , and coo lin g. Kilns havi ng a preheater and/or precalciner d o not usually contain the first thr ee zones. The m o ltenbatch e m erg es fro m the lower end of the k i l nin the f o rm of ver y h o t, marb le-sized chunks kn own as “clinker.” Once out of the kiln, the clinker goes through a c ooling process in the kiln cooler. When cool, the clinker is ready to pass through a series of grinding and milling processes that result in the gray powder we know
as ce ment. The kiln is the heart of the plant and is genera lly lined with fired bri c ks. Monolithic refractories are used onl y in tapered parts of the inlet cham be r, the manhole of th e calciner, an d the chargin g inlet of the kiln. These m o nolithics are required to posses high resi stance to reaction with cement
raw material s, high resistance to penetration/in filtration of alkalis, as well as high resistance to mechanic al stress. G e nerall y, dense low-ce ment , high alu m ina cast ab le with service te m p eratur es of 170 0–1 80 0°C (3092 –3 272°F) is used here. A typical long kiln will include a dr y i ng zone , a preheating zone, a calcining zone, a burning zone, a transition zone, and a cooling zo ne to cr eate a te m p erature p r ofile in the kiln. Generally, fireclay brick s or high-alum ina bricks are used in the dr y i n g and c a lcining zone s. Lightweigh t insulating bricks are used t o reduce the heat lo ss from the kiln. In these zones, refractorie s ar e subjected to abrasion and structural spalling caused by reactions withalkali from the ce ment raw materi als. The te m p er ature is relatively low inthese zones, but because of the use of various waste s as fuel and constant te m p erature f l uctuations, the refractory wear c an bec o me sever e. Fuel types vary am ong petroleum coke, tires, solid wastes , etc., resulting in i n creased concentrations of alkalis (Na, K), sulfur (S), and chlorine (Cl) as well as other enviro nmen tally detr i m ental metals (Pb, Zn). As a results, the refractorie s ar e subjected to harsher alkaline sulfate [( K 3 Na(SO 4 ) 2 , K2 SO 4 ] and alkaline chlori de (KCl, NaCl) condensation at cooler zones. Sulfur a dditionall y co m b ines with the cem e nt co m ponent ( C aO) to form CaSO 4 cotec tic liquid. These liquid and vapor phases infiltrate into bricks, resulting inrefractory densification, increased therm a l conductivity, and thermal expansion whi c h ultim at ely reduces the structural flexibility of kiln linings. Add i t i onall y , th e in crease in therma l conductivity often damages the steel shell.
Monolithic refractories ar e also used in sections of cement kilns, typically at the outlet where wear rat es ar e very high. At these zones, de nse silicon carbide–based castables ar e often used. The cy clones in the preheater section of ce ment plan ts are also lined with dense castables, due to the com p lexityof their sha p es and the wear resi st ance required. Th e shell of the exhaust gas duct is m a de fro m both dense and insulating castable materi al. In the cooler section of the plant,
m onolithic refractories are used to line th e ceiling. The upper and middle cy clones of the calciner are generally lined with fireclay castable or equivalent gunning m aterials posse ss ing a service tem p erature o f 1400–1500° C (2552–2732°F). One co mmon problem with this arrangem e nt ari ses when ce ment raw material s reach the inlet cha m be r and riser because they adhere (stick) to the refractory lini ng and thus c ause clogging . This cl og is either m ech anically rem oved or rem oved with high-pressure wat e r.
In the United States, as in m o st industrialized countries, two types of manufacturing processes have beco m e prevalent in th e cement industr y ; these are known as the “wet process” and the “dr y process.” Although in m any respects these processes are the same, or ver y sim ilar, in the ol der wet process, ground raw materi als ar e mixed with water to form athick liquid s l urry , while in the dry process crushed lim e s t one is used and raw materi als are mixed togeth er without the addition of water, lead ing to higher energy efficiency , since drying is not needed. Currently there is a general trend in the United States to convert wet kiln t echnolog y to dr y kil ntechn o log y ; as a result, in 2000 there were 32 wet and 77 dr y kilns.

31Appendix A — Chemical and Petrochemical

The major fuels used in U.S. ce m e nt plan ts are co al and coke, or coal and petrol eu m , and are used for the clinke ring process. After 1980, however, other fuels—including tires, sol i d and li quid hazardous wastes, and nonhazardous wastes such as o ils and solvents—began to be graduall y used. The use of these altern ative fuel types h as significantly increased in recent y ears, as shown in Table A.1. Overall, this suggests that there have bee nno m a jor changes in energy -efficient fuel use in cem e nt kilns since 1990, although m o re m ode rn plants have been built. T h e survey , by th e Portland Cement Associati on (PCA), suggests sli ghtly lower avera g e energy uses of 4.73 GJ per million m e tri c ton of clinker and 4.91 GJ per m illion metric ton of Portland cement for 2000. Further, the 1 997 Eco nom ic Census rep o rt (s am pling 279 establishm ents) showed that energ y costs (fuel costs and purchased ele c tricity costs) acco unt for 40% of the total cost for the ceme n t industr y , withapproxim ately $485 m illion sp ent on fuel and a sim i lar am ount spent on electricity

. 7

Table A.1. Fe edstock for energy use in the cement industry, 1993 -2001 (thous a nd m e tric tons )

1 993 1 994 1 995 1 996 1 997 1 998 1 999 2 000 2 001 % chan ge C o al 10 ,0 3 4 10 ,4 8 4 8, 24 1 8, 76 4 9. 03 5 9, 06 6 9, 20 6 10 ,0 9 5 10 ,2 4 0 2. 05 C oke from coal NA NA 45 5 45 8 35 1 43 2 34 3 44 2 42 0 –7 .6 9
Petrole um coke NA NA 1, 47 5 1, 29 5 1, 28 8 1, 19 7 1, 62 2 1, 35 1 1, 37 0 –7 .1 1
Fu el o ils a 46 49 42 64 86 73 82 12 4 93 10 2. 2 Natural gas b 66 8 65 0 1, 06 9 71 0 67 2 72 0 65 3 33 8 39 7 –4 0. 5
Ti res 70 12 0 15 8 19 1 27 7 26 9 68 5 37 4 30 0 32 8. 6 So lid wastes 90 74 68 72 68 74 81 6 1, 01 6 32 0 25 5. 6
Li qui d wastes a 74 4 60 0 88 5 91 0 83 5 1, 26 8 90 6 92 9 82 9 11 .4

a Millions of l i t e rs. b Millions of cub i c lit ers.

Barrier s Refractories play ke y role s in calcining operati ons, th e core production m e thod for the cem e nt and lim e industries. It is estim ated that alm o st all of the energy cons um ption is affected by refractories. Reco mmended im provem e nts for refract ories include applications for all of the therm a l zones of typical rotary calciners. Based on subsequent analyses of typical furnaces and unit pr ocesses, i m provem e nts to refractory s y stem s fo r the cem e nt and lim e industries could lead to op portuniti es for energy savings of up to 42.3 TBtu/y ear. The specific barrier s are shown below.

• Unavailability of chrom e -free re fractories for use in the trans ition zones of lime kilns, where refractorie s ar e subjected to large te m p er ature fluctuations b y th e repeated detach ment and adhesion of th e cement coating.

• Unavailability of refractories with adequate corrosion resistance an d adhesion (c oating) ability for use in the burning zone of lim e k ilns, where tem p eratures reach to above 1450°C (2642°F).

32Appendix A — Chemical and Petrochemical

• Unavailability of refractory m onolithics with high abr asion resistan ce as well as high resistanc e to mechanic al and therm a l sp alling for the inlet cham ber and riser of kilns to replace less adherent silicon carbide cast ables and precast shapes.

• Unavailability of m onolithic refractory materi al s withresistance t o alkali reacti on for use as clinkers in the cooling zone of the kiln to replace low-ce ment, high-alu m i na cast ables used in the area.
R&D Pathw ays

• Develop m o n o lithics with better abrasio nresi stance and low or no adherence properties.

• Develop methods to m odif ythe surfaces of c linker zone brick, so a s to encourage the formation of protective coatings by physically altering the refractory surface or through che m ic al alte ration of the s urface. Devel op and im prove magnesia- spinel brick and dem onstrate th e effect of zi rconia additions.

• Identify non-chrome-conta i ning refractories wh ich posses s increa se d corrosion re sistance to the environm ent present in ce ment m anu facturing.

• Develop non destructive techniques for m onitoring wear of refractories.

• Develop and i m prove silicon carbide castables to produce products with im proved thermal properties and even less adherence to ce ment raw mat e rials.



## A.3 Chemical and Petrochemical

Current Ind u stry Ope r ations and Refractory Use The chem ical industries have processing equipm ent that spans a broad range of types, with associat ed processing temperatures ran g ing from as low as 370–425°C (700–800°F) to as high as 1870°C (3 40 0°F). The refractory

- lined un its in a typic a l full-spectrum refinery can include fluidized cataly s t cracking units (FCCUs ) , cataly tic reformers, fired heaters, boilers, hy drogen reform er s, ethy lene furnaces, incinerators, and carbon furnaces. Some of these units are designed to have substantial insulating capability in their linings, while others are low-temperature-process units, like FCCUs that contain only a single lay e r of re fractory designed to withstand the extre m ely severe abrasion c aused by the cataly s t.
The esti m at e dcost of refractory lining installation and m a intenanc e work for the che m i cal an d petroleum industries is relatively low (as low as 1% of the total oper ating cost) com p ared to oth e r equipm ent co nstruction an d m a intenance costs; y e t, r e fractory lini ng degradatio n and failure are leading factors for frequency and d uratio n of s hut downs. Due to lo wer operating tem p erature, as co m p ared to other industries, refra ctory is not norm a lly affected by high tem p eratures, y e t refractory de gradation m ay be caused by erosion, corrosion, and m echanical str e sses caused b y therm a l cy cling, depen d in g on l o cation of the refr actor y within th e unit. Anoth e r problem th at can affect refract or y reliability is the manner in whic h the refractory is installed (i.e., pneum aticall y gunned, shotc r eted, vibration cast, pum p cast, and/or hand packed)

. Additionall y, with operati ng time, m i nor im p e rfections can beco m e l o cations of exacerbated li ning degradation. Lining design (i.e., anchoring, lining thicknesses, and design of construction/expansion joints) can also add to lining degrad ation.

33Appendix A — Chemical and Petrochemical

Also, the total tonnage of refractories in an av erage-sized full-spectrum re finery can be as high as 1000 tons of refractory for a single lining that is in tended to last for at least a decade: a typical refinery requi res approximately 2500 t o ns of refract ory
. Som e of the m o re critical units are put on maintenance, with annual t urnaround, and the re placement and repair of refracto r ies for a single unit can am o unt to 250 to ns, or a fourthof the li nin g
. Virtually all of the refract ories used by chem ic al plants are m onolithics. These include castabl es, cast vibration m i xes, gunni ng m i xes, low- and no-cement cast ables, plastics, an d a variety of insulating refractories. Be c ause many of the te m p eratu r es of refineryprocesses ar e too low to prom ote a cer a m i c bond to replace the hydraulic bond of calciu m al um inat e–bonded castables, the refractory practice has been based largel y on phos phate-bonded plastics, which develop the needed prope rties at or below the process te m p er ature s . Refractory practice varie s widely from
one com p any to another. Some co m p ani es have incorporated castab les, especial ly vibratables, into their practice, and today com p anies are ev aluating shotcretable refractories i nlocations where a ceramic bond can be developed at the process tem p er ature. However, the place where advances in refractories may have the greatest i m p acton efficiency in the chem ical industr y is i n the boilers used to pro duce steam for power generatio n. Im provements in the therm a l efficiency of boilers thems e lves, throug h im proved insulation, an d in the i n sul ation used on trans f er pipework could lead to reduc tion in h eat loss and lower fuel consu m ption. In the petroch e m i cal and synthesized gas industr ies in particular, new designs in th e cataly s t support m e dia and the inst allation of refractor y insulation have incr eased operati on life and efficiencies of reactors of various types. New ref r actory designs for support m e dia have allowed increased flo wrate and longer productive life for expensive catal y s t m aterial s. More attention being paid t o the use of spray a ble refractor y cera m ic f i ber lining materials as we ll as new microporous silica backup materi als. More attention is also being pa id to th e use of precast part s for com ponent of the various unit pr ocesses, and wider use of precast technology is anticipated. Because it is so im portant to m a intain sh ell te m p eratur es of vessels and reactors above a threshold te m p erature t o avoid condensation onto the shell, designers are try i ng to refine th e m odels for predicting te m p erature gra d ients and cold face te m p er atures. Lack of data on the thermal conductivity of many comm erci al m onolithic refractor ies is holding back progress in this area.
Barrier s Refractories and insulatio n materials play ke y rol es inm o st of the varied unit ope rations invol v e d in the pro duct i on of chem ical and petrochem i cal products; it is estimated that ab out 5 0 % of th e industries’ dir ect energy consum ption is in processes affected by ref r actories. Based on subsequent analy ses of typical furnaces and unit proc esse s, i m prove m e nt of refr actory s y stems for the chem ical and petrochem i cal industries coul d lead to energy savings opportunities of up to 266. 4 TBtu/ y ear. The specific barriers are shown belo w.

• Lack of unde rstanding of h i gh-tem p erature properties such as creep rupture, shor t-time strength, ther mal conductivity , th ermal expans ion, ductility , and st ability for th e m onolithic refractories used in this industr y
.

• Lack of unde rstanding of th e corrosion properties of refractories used in the chemical and petrochem i cal industries, which subject mate rials to conditions ranging from hot-oxidizi ng environm ents to environm e n ts that contain hot haloge n gases or gases with entrai ned particles.

34Appendix A — Chemical and Petrochemical

• Lack of unde rstanding reg arding tur n around tim es and m a intenan ce costs, which have beco m e increasingly m o re im portant cost el em ents. Lack of understanding regar d ing th e reduction of e n erg y consum ption and air polluti on.

• Lack of unde rstanding reg arding hi gh-t e m p erat ure and corrosive environm ents which lim it refractory life and increase maintenance costs in num e r ous che m ical and petroche mical reactors.
R&D Pathw ays

• Develop im proved refractories for m i nimizing m ech anical dam a g e to refractory

- li ned refining vessels through reduction of th e am ount of m e chanical stresses on the lini ng.

• Perform work to opt im ize the phy s ical properties of refractories (i. e ., thermal insulation, erosion resistance, corrosi on resistance, therma l shock resistance, strength, p o ros ity, and perm eability ) under known required ope rating cond iti ons for specific unit types. Develop realistic and reproducible product development and quality control t esting that can be used to relate st ep i mprovem e nts i nneeded physical properties of the current refractory lining materi als in s e rvice.

• Develop im proved m e thods of anal y s is for hi g h -tem p e rature equipment throughtechniques for online refractory inspe c tion.

• Develop longer-life refract ories that are fi eld-repairable, less brittle, and m o re sh ockresistant.

• Acquire therm ophy sical, kinetic and mechanical data on refractories.

• Develop ceramic- m etal- m atrix com posi t es w ith i m proved stability and explore s urface
m odification and/or coatin gs for use in corrosive environm ents.

• Develop materials to withstand hig htemper atures (1000–3 000°F) while retaining superior strength, duct ility , corrosion and wear resistan ce to resist dam a ge du e to corrosion and hi gh tem p eratures present in the chem ical process industry

.

• Develop mate rials with enhanced resist an ce to organi c acid environments and im proved materi als for chlorine-based processes, t o im prove plant operations and m a intenance require m e nts and reduce costs.

• Develop refra ctories and refractory coatings for high-te m p erature fu rnaces to redu ce energy and m a intenance costs. Develop hi gh-te m p erat ure nonstick surfaces that do n o t degrade or beco m e volatile at high te m p eratures to help reduce needed m a intenance of chemical process equipm ent.



## A.4 Forest Products

Current Ind u stry Ope r ations and Refractory Use Althoughthe pulp an d pap e r industr y is not a substant ial user of refractories, the forest product s industr y is th e third largest consum er of energy i nthe United States, at approxim ately 3. 3 q u ads per y ear. 8 To its credit, the industr y generates 63% of its own energy using rec y c l ed woody w aste products and other renewable sources for fuel (b ark, wood, and pulping li quor)

. Since 1972, th e industr y has reduced its use of fossil fuels and purcha sed energy by about 2% while increasing total production by nearl y 64%. In the f u ture, bl ack li quor and biomass gasification will lead to

35Appendix A — Forest Products

greater reduct i ons in purchased energy and coul d even change the pulp and paper industr y fr om a net energy importer to a net energy expor ter. Gasi fication h o lds the prom ise of generating 17 5 %
m o r e power than do current Tom linson furnaces, but the gasification technology currently in place requires y early refractory relines of the vessels. 9

Lim e recovery kilns are us ed in m o st forest pr oducts industries as an integral co m ponent of the Kraft pulping process, with lime recoverykilns op erating at a level of 7 m illion Btu/ton of lime recovered. Y e t, these kilns have the disadvantag es of cy clic production rates, poor product quality , dust cy cles, rings, materi al buildups, and bloc kages. Most of these deficiencies c an be related to premature brickwork failure and buil dups, with loss in productio n of up to 35 days per y ear being attributed to ri nging.
Barrier s It is estim ated that about 4 0 % of direct energyco nsum ption by the forest produc ts industr y is in processe s aff ected by refractories. Bas e d on su bsequent analy ses of typical furnaces and unit processes, i mprovem e nt of refractory s y stems could lead to energy savings opportunities of up to 129 TBtu/ y ear. Specific barriers are shown below.

• Lack of unde rstanding regarding problems associat edwith sticking of reactants and products to the refractor y lini ngs of lime kilns, limiting their operating lives.

• Unavailability of m ateri als with corrosion r esistance t o the harsh, high-alkali bla c k sm elt environm ent (consisting of steam , sulfur, hy dr ogen, and CO) and abrasion/erosion resistance, spall resistan ce, and thermal co m p atibility with m e tall ic m ateri als u sed in the gasifiers.

• Unavailability of im proved m at e rials fo r containm entwhich do not react with the high-alkali at m o sphere p r esent in the gasifier. Such reacti ons res u lt in slabbing, which lim i t s the lining life.

• Lack of a database on the properties of the castable materi als use din this industry , inform ation which is not provided b y th e refractory producers.

• Unavailability of im proved refractories for Tom linson recovery boilers to replace fireclay , alu m ina brick, or sim ilar monolithic compositi ons use din the fl oor. Im proved refractories could decrease the am ount of furnace downti m e needed for repairs and woul d decrease energy usage due to shutdown and restart cy cles.

• Lack of refra ctory s y stem s with sufficient al kali corrosion resistance for storage container linings used for hot pulping chem i cals.
R&D Pathw ays

• Develop im proved refractories for lim e kilns to reduc e downtim e du e to ringi ng and buil dups, thus leading to increases inenergy efficiency due to better therm a l manage ment and increases in lim e kiln lining lifetim es.

• Develop advanced refractories to provide su itable mate rials for use in black liquor and biom a ss gasif i ers. Advance drefractories could lead to substantial im provements in energy efficiency for the forest pro ducts industr y, which curr ently requires y early refractor y relines of the vessels

.

• Develop mate rials with greater resi stanc e to the corrosion in m o lten salt environments, greater abrasi on/erosion re sistance, and greater sp all r esistanc e . In addition, develop alternate refractory sche m e s to provide refractory surface s whic h are m o re i mpervious to w ear and

36Appendix A — Forest Products

corrosive atta ck through coatings, che m i cal alter ation of refractory surface s, physical alteration of refractory surfaces, et c.

• Develop refractory m aterial s which are more th erm a lly com p atible with metallic materi als used in gasifiers.



## A.5 Glass

Current Ind u stry Ope r ations and Refractory Use The glass industry produces a wide variety of pr oducts using differe nt process technologies. Perceived differences acro ss the seg ments of the glass industr y remain a barrier to broad-based industr y colla boration. T h ese differences have le d indi vidual segm e nts to select different m e lti ng technologies, prefer different refractories, and operate furnaces that differ in size and scale. Capital and operating costs for the indivi dua l segments reflect these product and process differences. F urther, differences in glass types and industry segm e nts and the needs of large versus small furnaces li m it the ability to define co mmon interests. There are al so concerns with project defini tion and m anagem e nt for cooperative e fforts: costs, timing, and shar ing of techni cal and financial risks and the i n tellectual property generated. Melting of the batch is acc om plished us ing differe nt types and sizes of furnaces, with refining occurring in th e melting cham ber. Furnaces may be di scontinuous ( < 5 ton/day ) or continuous (large operations, esti m ated to last up to 10– 12 y ears today ) . Cont i nuous fur n aces may be directfired (units fi red with natura l gas and producing 20–150 ton/day ) , r ecuperative f urnaces (directfired furnaces fitted with recuperators to recove r heat f r om exhaust gases), regen e rative furnaces [ the m o st commonly used furnaces, withcapac ities o f 100–1000 t on/day , and with the furnace heat collectedin a regenerator that is used to preheat com bustion air as high as 12 60°C (230 0°F) and achieve higher energy efficiency ] or all-electric melters.
Co mm only , a l um ina- zirco n ia-silica refr actories ar e used as sidew a lls, with zirconia content ranging from 33 to 41%. Chrom e - c ontaining refractories are al so used in the fiber g lass industr y because of their additional corrosion and erosion resi stance, but their use is decreasing because of environm ental concerns about chrom e . Refractories containin g chr o me are not used in the flat, container, or pressed/blown glass industr ies becau se chrom e i m puri ties can disco lor the glass. Silica is co mm only used for the crown of the furn ace, or som e ti mes m u llite if oxy -fuel firing is
em ploy ed. D u e to chem i c al incom p atibilities, a lay e r of alum ina-zi rconia-silica i s often used as a buffer between the crown and sidewall. 1 Significant pr ogress has been made in reducing en ergy intensity i n areas of the glass industry over the last ten y ears. This increase in ef fi ciency has been acco m p li shed m o stly through i m proved process control sy stem s, the development and use of advanced refra ctory m ate rials, and technologies such as oxy -fuel firing and electric boost, which increase production capacity

. Advanced technology has reduced the fuel cons umed per ton of glass m e lt ed by 25% since the early 1980s, and energy use has declined in the fibergl ass sector by 30% since 1978. 10 Still, energy e fficiency depends on the si ze of the operation and the production rate. For exam p l e, a large (120 t on/day ) all-el ectric furnace uses electri ci ty at 66% ove rall efficiency , while a sm al l all-electri c furnace (4 ton/day ) has about 34% overall efficiency

. 11 Electric glas s- melting furnaces
are m o re thermally efficient than oxy-fuel becau se th ere is les s ma ss ( m elt basin only ) and less surface ar ea f o r heat losses. Average oxy -f uel me lters consum e 3–5 MMBtu from fossil fuel per

37Appendix A — Glass

ton of glass melted. This is in com p ari s on with the av erage electri c consum ptio n of all-electric direct resistan ce glass melt ers of about 2.7 MMBtu/ton. Yet, m odern glass m e lting still requires a high-tem p er ature device that consum es a significant quantity of energy , with m e lting energy r e presenting about 15% of th e manufactu r ing costs. Although ther e are so me proven energy -r eduction technologies for melting that are not current ly being im plemented and so me con cepts which have been identified to further reduce energy
consum ption (i m p rove m e n t s in corrosion-resistant ref r actories, ins u lation, com bustion, process control), the e c onom ic incentive for adopting th ese proven technol ogies and developing th ese new concepts may not currently be sufficient to justify the cost and the effort. This m ay be because the i ndustr y views m i ni m i zing the energy cost per ton of glass produced as m o re im portant than reducing th e energy cont ent as m e asur e d in therm a l units and bec ause the value of the energy saved at the current cost of energy , w ith anassu m e d low rate of costescal ation, is not sufficient to justify m any energ y -saving technologies. In particular, technologies th at require any significant capital investment are usually di scarded by the glass industry or looked upon unfavorably , with many glass manufacturers expecti ng a one- to two-y ear payb ack for capital invest m e nts. 12 Specific energy usage by sector is shown in Table A.2.

Table A.2. Es timated ener gy use in melting and refining Av. speci fic Ann u al Glass s ector energy use energy use (1 0 6 Btu/ton) (10 TBtu) Fl at 8. 6 42 .9 C ont ai ne r 5. 5 53 .1 Presse d/ bl own7. 3 18 .1 Fi ber 8. 4 25 .6 Source: DOE, Energy and Environmental Profile of the US Glass Industry, DOE/GO -102002-1590, Office of Indus trial Technologies, April 2002.

Oxy

- f u el firing is also still a viable technology and could im prove efficiency in th e glass industry

. The trend towards using oxy -fuel firing is st eadily increasing because an oxy -fuel furnace can produce the s a m e am ount of glass as wi th gas and/or air, but at a lower fuel input. 13 Additi ona lly, when regenerative furnaces are conve rted to oxy -fuel firing, the regenerator refractory str u cture is not needed, el im inating the exhaust volum e by as m u ch as 75%

. 14 As of 199 8, o n l y20% of the glass furnaces in the United States had been convert ed from air-fu el to oxy-fuel t echnology, with the greatest conversion rat e found i nthe fibers sector. 15 To date, it is esti m ated that the num ber of conversions h as increased onl y t o aroun d 25% of the total industr y. 15 A breakdo wn of the num b er of conversions to oxy

- f u el t echnology com p l e te d by 1998 i neach sector of the gl ass industry i s shown in Tab l e A.3, along with estim ates of the num ber of conversions m a de to date. Therefore, there is still a great opport unity f o r further im provements in the energy efficiency of the glass industr y th rough further ut ilization of oxy -fuel fi red furnaces. Further im provements in refractory technolog y are needed to full y uti lize the benefits of ox y -fuel technolog y. Boosting withoxygen firi ng will result in increased production but will also increase the melti ng cost per ton of glass. This trade-off is accep ted by the industr y because the additional capacity gained is at a m u ch lower c a pital cost than th at associa t ed with building new furna ces. Sa m p lin g of the industry indicates that to date, 125–15 0 of 500–550 total gla ss furnaces h ave been

38Appendix A — Glass

Table A.3. Conversi o n of No rth American gl ass m e lter s to oxy-fuel fi ring as o f

199 8 and a s of 2 004

Glass s ector N o . o f ox y-f u el conversions To ta l no
. of gl ass t a nk s % converted

C ont ai ne rs 23 21 0 10 Fibers 41 11 0 37 Tex tiles In su latio n (3 0) (1 1) (7 0) (4 0) (4 2) (2 7) Fl at 2 45 5 Speci al ty54 23 5 23 Al l sect ors 12 0 60 0 20

C ont ai ne rs 27 18 0 15 Fibers 46 10 0 46 Tex tiles In su latio n (3 5) (1 1) (6 2) (3 8) (5 6) (2 9) Fl at 3 45 7 Speci al ty60 22 5 27 Al l sect ors 13 6 55 0 25 As o f 19 98

As o f 20 04 (est im a ted )

converted to oxy -fuel firing. This is onl y25% of all th e furnaces i nthe industr y , leaving a large
num ber of furnaces that co uld be converted to th e m o re efficient technology , leading to poll u ti on abate m ent and higher energy efficiency , if im proved alternate refr a c tories with s u fficient corrosion resistance and therm a l efficien cy cou l d be f ound . Of the various segments m aking up the glass industry , the fiber area has mad e the m o stuse of oxy

- fuel firing, with nearly 50% of these furnaces having been converted; in second place is the special ty area, with over 25% of th e furnaces converted. Great o pportunities exist in the flat and containe r glass seg ments, which have conversion rates on the ord e r of 5 to 15 %

. Barrier s Refractories and insulatio n materials play ke y roles inmany of the unit o p eration s involved in the glass producti on; it is estimated that about 70% of th e direct energy consum ption is in processes affect ed by refractories. Ba sed on subsequent analy ses of typical furnaces and unit processes, i m prove m e nt of refractory sy stems for the glass industry could lead to energy savings opport unities of up t o 13.9 TBtu/ y ear. Specific barriers are shown below.

• Unavailability of durable and inexpensive m ate rials fo r use for refractories in constant contact with m o lten glass, co m bustion gases, and hot glass product s in glass furnaces which operate continuousl yat tem p eratures exceeding 1400°C in the molten bath and 1600°C in th e co m bustion atm o sphere for operating liv es of 8–10 y e ars.

• Unavailability of parts and installation equipm ent to replace parts and m ateri als th at fail during prod u c tion cam p aigns, without major furnace shut-downs and loss pro du c tion.

• Li m itations on energy efficiency and degradi ng glass quality , particularly in oxy-fuel environm ents, due to l i m itations of refractory performance.

• Lack of know ledge that would im prove the pe rformance and quality of existing r e fractories and lead to increas ed production life and lower installa tion costs.

39Appendix A — Glass

• Lack of m odeling of corr osion m echanisms that would help determine solutions for reducing corrosion in r e fractories and for pr ovidi n g ad equate on-line sensors that would opti m i ze operation control, leading t o longer-life, co rrosion-resistant refractor ies, thereby reducing capital costs f o r glass m e lti ng and form i ng applications.

• Lack of know ledge in the f o rm of a materials property database, identification of new m e lting techniques and their associated refractor ies, a nd better methods for th e evaluation and repair of refractorie s in service.
R&D Pathw ays

• Develop integrated furnace m odels for the prediction of methods for im proving th erm a l efficiency , fo r developin g new glassmaking techn o lo gies, and for projecting per f ormance of alternate refr actory m aterial s.

• Develop refra ctories (partic ularly for furnace crowns) having sufficient strength and corrosion resistance at higher operating t e m p eratures when using o x y gen enrichment.

• Develop m o n o lithic and/or coated refractories th at will be m o re resi stant to penetration of corrosive liquid and gaseous specie s
.



## A.6 Heat-Treating and Annealing

Current Ind u stry Ope r ations and Refractory Use Heat-treating is a $20 billi on industr y in the Un ited St ates and represents $75 bill ion or m o re in value-added manufacturing glo b all y
. 16 I t is also crosscutting, enabl i ng technol og y that affects
m o st of the in dustries foun d in the Unite d States, including alum inum , glass, iron and steel, and metal casting. The goal of th e Heat Treating In dustr y Vision 202 0 i s to reduce energy usage in the heat-treating industr y b y 8 0 % . To achieve this goa l, co operation is n eeded between all the related industrial gro ups, includ in g the heat treating co mm u n ity , m e tal producers, foun dr y and f o rgi ng groups, fabric ators, government, and academ i a.
One of the most im portant research needs for th is industry is the development of integrated process m ode ls. Heat tre ating today is viewed as an experience-bas e d art. However, in the future it m u st functi on in a scienti fic, predictive envi ronm ent, where processes ar e truly understood and capable of being sim u lated

. For exam ple , it has been de m onstrated th at the solutionizing tim e for a cast alu m inum alloy could be reduced from 12 to 2 h with no los s of qualit y or properties. This magnitude of heat treatment cy cle tim e r e duction coul d result in inc r eased productivity and/ or reduced energy consum ption of greater than 50%. Validated databases for m u lticom ponent alloy s and predictive m odels will enable co m p arable resu lts to be achieved for a wide range of allo ys and applications. 17

Barrier s Refractories and insulation materi als play ke y rol es in various furna ce sy ste m s us ed in the heattreating and annealing in du stries; approxim ately90% of direct energ y consum ption is in processe s aff ected by refractories. Bas e d on su bsequent analy ses of typical furnaces and unit processe s, i mprovem e nt of refractory s y ste m s for the heat treat ment and annealing industries could lead to energy savings opport unitie s up to 45 TB tu/ y ear. Specific barriers are shown below.

40Appendix A — Heat Treating a nd An nealing

• Unavailability of hi gh-perf ormance refractories fo r the im provement of therm a l efficiency in furnace sy stems that would lead to reduced cy cle times, lower requ ired energy i nput, and lower process ing costs.

• Unavailability of gradient refractory s y st em s with lower thermal conductivity and hi ghte m p erature s trength and c o rrosion/erosion resistance for reducing heat losses an d im proving chem ical co mpatibility
.

• Unavailability of refractory m at e rials with longer lifetimes due to im proved corrosion resistance, extended tem p erature resist ance, and mechanical thermal stability , wh ile also possessing re duced costs.
R&D Pathw ays

• Develop im proved insulati on m aterials to achieve hig h er operating tem p eratures, reduce heat losses, and eliminate rehe ating while also reducing process ti me an d production costs.

• Develop higher-effici ency insulation m a terials to increase the thermal effi cienc yof current processe s and si m u ltaneously lower heat-treatment ti mes, leading to significant reduction of energy co nsum ption levels. This could th en lead to th e developm en t and application of accel erated h eating technologies, which will re quire alternative insulation m ateri als with greater thermal shock resistance and high-tem perature stability

.



## A.7 Iron and Steel

Current Ind u stry Ope r ations and Refractory Use In the steel industr y , com p etitive pressures such as worldwide over capacity , the high cost of energy , environm ental andsafety regulations, com p et ing m ateri als, customer de mand for high quality , and th e high cost o f capital have led to a need for sweeping changes across the industr y. Therefore, four critical areas for im provem e nt or targets of opport unity were identified: (1) process ef ficiency thr o ugh im proved throughput , quality , and energy efficiency, (2) increased recy cling, ( 3 ) new processes to avoid or reduce air and water pollut i on, and (4) product developm ent. 18 As part of the approach to address these areas, r e fract ories currently used throughout th e steel making process wer e analy zed. Oxide-based cer a m i c s of alum inu m , calciu m , zir c onium , chrom i u m , magnesiu m , and carbon are primarily use din steel cont act in an effort to reduce contam ination and interaction with th e h i ghl y alkaline slags. Nonox ide ceram ics consisting of
co m b inations of silicon, tit anium , tungsten, and alum inum are used for hot handli ng applications where therma l shock resistance, cre e p re sistance, w e ar resistanc e , and resistance to acidic spec ies is desired. These materi als may be in the brick or castable form . In many areas of steel furnac es refractory life is extended by splashing slag agai nst the refractory walls. This slag solidifies on the wall, forming a protective lay e r. T h is process, though highl y s u ccessful, is very i n efficient therm a lly

. Today , steelmaking from pig iro ncommences in the transfer ladle ahead of the basic oxygen furnace (BOF ) and continues after the B O F to the ladle stations and on to the tundish, which distributes the steel into the continuous casting or stationar y m o lds. Refractories for all these unit processes are select ed on the basis of their longevi tyand the cleanliness of the steel that passes throug h them. The cost per pound of refr actories for all the various co m ponents, with few

41Appendix A — Iron an d S teel

exceptions, has increa sed markedly with the awarene ss that advanced refra ctories can meet th e goals of greatly extended s e rvice and contribute to th e quality of th e steels.
In steel ladles , maintenance costs are high and h eat efficiency is poor. Currently , high-alum ina and m a gne sia

- based cast able refractorie s are preferre dfor ladle linings at and below the slag line due to the high process te mperatures, ero s ion fro m the stirred bath, and the high c o rrosiveness of the slag. Life is short for these refr actori es; theytypically last for only 30 to 50 heats. Highertem p erature-capable oxide/ carbon m i xtures have b eenevaluated for use to prov id e a balance between purity, therm a l sh ock resistance, and er osionresistance, along with othe r alternative refractorie s w ith longer life, lower cost, and safer disposal. Yet, no materi al of choice has been identified. Monolithics (refractory concretes and gunning m i xes) co m p rise at least 60% of all refractories used in iron and steel m aking in the Unite d States today (over 70% in Japan), and there is a stro ng trend to incre ased use of precast ver s ions of m onolithi cs. Installatio n practice has undergone
so m e major a dvances whic h translate to m u ch m o re rapid original construction, replace ment of working li nin g s, and repair. The adaptation of sh otcreteing methods from constru c tion concrete technolog y h as resulted in significant reductions in d o wntime and in som e cases longer service life as well. I nthe ladle lining practice, it has b een possible to succ essively repair the original lining such th at co m p lete r e lining is no l onger necessary
. Im proved materials for runners (used to flow th e m o lten steel fro m a BOF or an electric arc furnace to the refining ladl es) are needed. Th ese co mponents are generally constr ucted from fireclay brick, alum ina c ast able, or chromia ca stable. They experience corrosion, wear, and therm a l stresses that li m it their lives to one to two weeks. Sim ilar i m prove ments are needed for water- cooled pipes and stirrers enclosed in refr actory

. They also experience corr osion, wear, and therm a l stre ss es that li m it their life and require weekl yrepair. Energy consum ption in the various unit processes fou nd in th e iron and steel industry has changed substantially due to advances in refractory practice, but it is difficult to identify the role of refractorie s in energy savings because many change s are being made in designs and
co m bustion practic es as we ll as in metall urgical and slag practices. Some unit processe s like blast furnaces and BOF m e lt ers are designed to leak ener gy to induce a steep therm a l g r adient through the lining. In an extre m e e x a m ple of this pro cess desi gn concept, the walls and roofs of electric arc furnace s ar e water- cooled to cause the steepe s t possible therm a l gradient. Consequently , it i s in the other unit processes where refr act ory practice c ontributes to energy savings in several w ay s (e.g., m o re efficient insulation, extension of the tim e between maintenance shutdowns, reduction in the am ount of refractory scrap and reduction in m e t a l scrap through im proved cleanliness of the final steel products).
As mentioned, blast furnaces and BOF melter s are d esigned to leak energy , and even in the c ase of m o st ladles, insulation i s m i ni m i zed in the wa lls and bott o m s in an effort to induce a thermal gradient in the interest of reducing the r e fr actory wear. Ladle covers, on the other hand, are absolutely necess ary to conserve the te m p eratur e of the contained metals and are m a de fro m increasingly a dvanced materials. There ar e m any op portunities for direct ener gy savings in all of the unit pr ocesses and components in ir on and steel plants that are not designed t o incorporate steep thermal gradients. There are also opportun ities to extend refractory l i fe through th e use of lining th ickne ss m onitors and other sensors and instruments which im prove the com bustion efficiency and reduce stack losses as well as releas e of undesirabl e products of the processing of the iron and s t eel.

42Appendix A — Iron an d S teel

Significant i m provements are needed for m eeting operating challenges for m onolithic refractories. Monolithic linings possess many inhe rent problems. Ideally , steelmakers would like to have m onolithic linings for all of the ladles and even for the basic oxy g en furnace. The socalled basic li ning has recei ved considerable resear ch a ttention, but no reports of succes s in a BOF have been reported to date. Problems exist with the hy dratabi lity of the basic co m ponents of the products, which are based on MgO, ma gnesite, doloma (calcined dol om ite, CaCO 3 ·MgCO 3 ), and spinel. F urther, m onolithics for BOF linings need to incor por ate substantial am ounts of carbon in the form of graphite, and resear ch is ongoi ng to resolve the problem that derives from the interference of the high volum es of graphite with the binder s y st em s of the monolithics.
Barrier s Refractories and insulation materi als play ke y roles in the sm elting, refining, and melting operations us ed in the iron and steel industries; it is est i m ated that 85% of the industries’ direct energy consum ption is in process es aff e c t ed byrefractories. Based on subsequent analy ses of typical furnaces and unit processe s, i m pr ovement of refractory s y stems for the iron and steel industries could lead to ene r gy savings opportun ities up to 148. 5 TB tu/ y ear. Specific barriers are shown below.

• Lack of adequate corrosion resistance f o r refractorie s in contact with m o lten m e tal, which leads to unde sirable equipment lifetimes. This is especially im portant for refractories used in parts of furnaces, ladles, an d tundishes.

• Unavailability of im proved m aterials fo r runners (used to flow th e m o lten steel from a BOF or an electric arc furnace to the refining ladles), wate r- cooled pipes, and stirrers e n closed in refractory

.

• Lack of utilization of advanced m onolithics in ladles due to pr oble m s with their explosive tendencies an d lack of data on som e of the ke y inp u t properties and param e ters for m o st of the m onolithic products that m e et the requirement for steel ladle practice.

• Unavailability of im proved im pact pads at th e bottom of ladles, which experience high wear, therm a l shoc k, and abrasion.

• Unavailability of thi n -walled alum ina refractory ladle shrouds that are used to reduce oxy g en pick-up during pouring withlifetimes of greater than ten heats in the extreme conditions of this application.
R&D Pathw ays

• Develop methods for suppressing the hydration of m a gnesites.

• Develop refractory linin gs with im proved life and red u ced maintenance requirements, to reduce the y e arly or even m onthly m a i n tenance shutdowns generally necessary to repair refractory proble m s . Reduc ing the freque ncy of or eliminating these shutdowns would provide significant cost reduction, not to mention associated energy savings.

• Develop advanced materi als (such as refr actories w ith in situ coatings or externally applied coatings) for resisting corrosion/erosiondamage.

• Develop new materials alo ng with im proved m ate rials databases for mem b ers of the industr y to adapt to new m aterials i ntheir operat i ons.

• Develop im pr oved refractories for use in various parts of furnaces, heat processi ng equipm ent, la dles, and tundishes.

43Appendix A — Iron an d S teel

o Develop im provements in runners, water- cooled pipes and stirrers, which all experience co rrosion, wear, and therm a l i ssues that canlim it their lif e and require weekly repair.

o Develop im provements in materials and in stallation methods for ladle bottom s and im pact pads by using ceramic coatings or alternate localized mater i als.

o Develop long-lived, economically feasi ble, prefired refractory crucible linings for inductio n m e lting of stainle ss steel in air-melt operations.

o Develop im pr oved cera m ic /refractory materials for ne t shape steel c asting, eli m inating rolling m ill operations.



## A.8 Metal Casting

Current Ind u stry Ope r ations and Refractory Use Energ y consum ption for th e m e tals casting in dustr y is on the order of 0.2 quads per y ear. 20 Thi s resulted in an estim ated energy cost f o r th e f oundries i ndustr y i nthe United States of $1.2 billi on in 19 97 7 and $1.5 billion i n1998, 20 or a bout 10% of th e total m aterial cost put into pro duction and 4–5% of the value of t o tal shipm e nt. 21 Therefore, the industr y wishes to opti m ize melting, holding, and heat-treating furnaces to c onserve energy (i.e., to reduce energy us age by 20%) and mini m i ze pollutant em i ssio n s. Further, th e indus tr y w i shes to increase the life of refractories and other ceram i c com ponents that are exposed to m o lten metal s and/or furnace environm ents and develop in-line sensors thatare stable in the m o lten metal environment. 10 The unit pr ocesses utilized in the m e tal casting indus tr y are lined with a wide range of refractory
co m positions (including silica, alu m ino-silicate, high alu m ina, zirc on, m a gnesia, spinel, chrome, and m a gnesia-carbon) and forms ( m onolithics, precastshapes, and bricks). Most metals castin g industr y m e lt ing and holdi ng furnaces are lined with ceramic refr actories which are selected t o mini m i ze r e a c tion with the specific meta l being processed. Major refractory line dunits include reverberatory furnaces, crucible (pot) fur n aces, channel induction furnaces, corel e ss induction furnaces, electric arc furnaces, and pouri ng ladles. These furnaces are lined with wide ranges of refractory co m positions, including silica, alu m ino-s ilicate, high alum ina, zir c on, magnesia, s p inel, chrome, and magnesia-carbon. Substantial pr oblems do still exist with m o lten mate ri al containment and handli ng. For example, cupola linings for ferrous alloy m e lting usually requir e weekly repairs because of corrosion and mechanic al da m a ge. An alt e rnative to refractor y linings is “skull melting” (in tit anium melting, for exa m ple) where in a mechanis m si milar to th e slag splashing in the steel industry or the formation of a “frozen led g e” in the alum inum i ndustry , a protectiv e lay e r of m e tal is solidified on the containment vessel surface, cr eat ing a corro sion-resistant lay e r but lowering the thermal efficiency of the sy stem

. Iron foundrie s are the major energy consumer fo r this sector, repres enting about 12% of the industr y , f o ll owed by steel foundries at about 10%. Within each process, approxim at e ly 55% of the total energy cost is used for the m e lt ing of the m e t a l, with other processe s (core m aking, mold making, heat treat ment, and post-casting processes) accounting for th e other 45%. Although the total energ y cost (fuel + electricity ) accounts for o n l y about 1 0 % of the total m aterial cost, it can

44Appendix A – M e tal Casting

be as high as 20% or m o re for many f o undries depend ing o nefficiency an d the materials processed. Specific energy usage by the metal s castin g industry is given in Table A.4.

Ta b l e A
. 4
. P r o c e s s a n d e n er g yda ta f o r U. S
. me ta ls ca s t in g in du s t ry
Process Energy c o nsu m ption

Cupo la m e lt in g To tal: 8

. 6 × 10 6 B t u/t on C oke: 5. 8 × 1 0 6 Electricity: 1

. 1 × 10 6 Natural Gas: 1

. 6 × 10 6 Oxy g en: 0. 1 × 1 0 6 C o re m aki ng an d m o l dm aki ng 7 –20 % en erg y , 1– 3 × 1 0 6 B t u/t on

Electric m e ltin g Induction furnace: 4.3–7.6 × 10 6 B t u/t on Electric arc furnace: 4.3–5.2 × 10 6 Btu/ton Electric-resistan ce heated re verbe r atory furnace: 5.2–7.9 × 10 6 Btu/ton Gas-fire d m e lting furnace Crucible: 1.8-6.8 × 10 6 Btu/ton R e ver b .: 2. 5- 5. 0 × 1 0 6 Btu/ton Ref i n i ng an d po ur ing p r o cesses Electricity: 0

. 4 × 10 6 Btu/ton Nat ural gas: 0. 2 × 1 0 6 Btu/ton C l eani n g an d f i ni shi n g pr oces ses 1. 0 × 1 0 6 B t u/t on Investm e nt cast i ng Electricity: 3

. 0 × 10 6 Btu/ton Nat ural gas: 4. 0 × 1 0 6 Btu/ton Lost foam cast i ng 2. 5 × 1 0 6 B t u/t on Die casting Electricity: 4

. 0 × 10 6 Btu/ton Nat ural gas: 5. 0 × 1 0 6 Btu/ton Othe r casting proces ses Perm anent: 2.5 × 10 6 Btu/ton Sh ell m o ld : 2

. 5 × 10 6 Btu/ton Plaster m o ld : 3.0 × 10 6 Btu/ton So urce : En ergy an d En v i ronmen tal Pr of ile o f th e U.S. Metal Castin g Indu stry.

Although the service life of refractory linings fo r all foundr y practices has been extended greatly in the last decade, m any of the problem s identifie d above still persist. For exam ple, m o st channel and coreless i nduction furnaces in iron and steel foundries use spinel-form ing dry

- vibratable castable, a shift from the w e t ra mming practiced in the past. This extended the s e rvice ca mpai gn of the foundri es, but m e t a l penetration and chem ical corrosion by sl ag still persists. Also, there are few case studies that sh ow good refractory m a intenance m anag e m e nt, new refractory developm ent, or proper selection methods resulti ng i ngreat energy savings and reduced melting cost. With the ever-increasi ng dem and for qualit y cast metal, alloy com position, and innovative melting technologies, refractories sections have been pushed to m o re challenging positions. Research program s in refractories scien ce and t echnolog y i nthe Un ited States have never been as large and as com p rehensiv e as R&D program s for other industr y and technology sectors. Nonetheless, the metal cast ing industr y i s still one of th e largest industry sectors in the United States, and the refractories industr y is essential to it.
For steel casti ng, wear of refractories andreaction of the refractorie s with highly basic (c alciacontaining) sl ag can generate defect-forming in clusions. High-alumina refra ctories are gener a lly used throughout this area of the process, with a pplication of zirconia-based mate rials in areas of high wear and therm a l shock and m a gne sia-based mat e rials in area s of high slag corrosion.

45Appendix A – M e tal Casting

Carbon m at e r i als cannot be used for this application, as they react with oxi de-based refractories to form CO and with alum inum in steel t o form alu m i n a. Sim ilarly , silica-bas e d refractories cannot be used because of contam ination issues.
There is a serious lack of data on the mechanical, thermal, and chemical propert ies of m onolithic refractories; and m u ch of the data that exists is lacking in detail or is obsolete. There is onl y o n e reference source for such key data as strength, m odulus of elasticity, therm a l conductivity, he at content, permeability , th ermal shock and creep be havior; and this s ource was first available 15 y ears ago. Hundreds of ne w and update d versions of m onolithics are on the m arket today , but there is very l ittle design and other technical da ta available aside from the product data sheets, which do n o t list m u ch beyond bulk pro p erties and some typical values (not to b e used in design but only as guide for selec tion).
Barrier s Refractories are used throughout the vari ous un it proc esses found i nthe m e t a l casting industr y ; approxim atel y90% of the direct energy consum ption is in processe s affect ed by refractorie s. Based on subsequent analysis of typical furn aces and unit processe s, i m prove m e nt of refractory sy stems for the metal casti ng industr y c ould l ead to energy savings opportunities up to 8.5 TBtu/y ear. Specific barriers are shown below.

• Lack of methods and m aterials to reduce or elim inate refractory failure due to phy s ical erosion and c h e m ical corro sion by m o lten m e t a l and slags in nearly all stages of metal melting, refining, and pouring processes where refr act ories m ake co ntact with m o lten metal.

• Lack of methods and m aterials to reduce or el im inate refractory failure related to fusion of refractories and chem ical corrosion b y MnO and FeO in steel foundries where the m o lten steel is generally tap p ed at high tem p erat ures [ up to 2 150°C (39 00° F)] , and the common practice is to use low-cost silica, zircon, or alum ino-s ilicate ra mmi ng m i xes and plastics, especially in those foundrie s that appl y a c id melting practices in smaller furnaces.

• Lack of methods and m aterials to reduce or elim inate cloggin g or b u ild-up form ation in channels and throats is problem atic for m o st m e tal casting operatio ns.

• Lack of methods and m aterials to reduce or el i m inate refractory wear in electric arc furnaces for the m e ltin g of steel, where reduced refractory wear and energy savings woul d be especially beneficial.

• Lack of methods and m aterials to reduce or el im inate wear and reaction of refractories with highly basic (calcia- containing) slags for steel ca sting.

• Lack of data on the m echanical, therm a l , and chem i c al properties of m onolithic r e fractories, with m u ch of the data that exists lacking in detail or bei ng obsolete.
R&D Pathw ays

• Develop im proved refractories that will resist phy sical erosion and c h em ical corro sion by
m o lten metal and slags. Specifically , develop m ateri a l sy stem s for steel containment that are chem ically st able with the m o lten metal and th at provide mechanic a l integrity aga i nst wear and abrasion.

• Develop im proved refractories which are resist ant to corrosion by MnO and FeO to prevent fusion of refractories in ste e l casting.

46Appendix A – M e tal Casting

• Develop refractories which will resist the adhesi on of m o lten metal that results in clogging or build-u p form ation in channels and thro ats.

• Develop im pr oved refractories for use in electric ar c f urnaces for the m e lting of steel that will resist wear an d prov ide energ y savings thoug h im proved insulatio n.

• Determine the m e chanical, therm a l, and chem ic al properties of m onolithic refractories used in the m e tal casting industr y.

• Develop nove l low-cost and hig h -perfor m ance m onolithics (in particular for iron , steel, and alu m inum fo undries), basic gunni ng m i xes, and Mg O-graphite castable for rapid repair of electric arc furnaces.

• Develop and m odel sl ag chem istry com p atible with refractory linings and m a xi mize the sl ag foam ing prop erties, along with efforts to reduce or elim inate repair and patching of electric arc furnaces due to refractory wear.

47Appendix A – Referenc es



## A.9 References for Appendix A

1. D. W. Freitag and D. W. Ri cherson, Opportunities for Advanced Ceramics to Meet the Needs of the Industries of t h e Future, DOE/ORO 2076, U.S. Departm e nt of Energ y , Office of Industrial Technologies, Decem b er 1998. 2. Alu m inum In dustr y Techn o log yRoadmap, The Aluminum Association, Februar y20 03. 3. A. T. Taberaux, “Recent Develop m entin Re fractories for Alu m inum C e lls,” pp. 271–81 in Proceedings of the International Sympos ium: Advances in Refractories for the M

e tallurgical Industries II, ed. M. Rigau dand C. Allaire, Montreal, Quebec, August 4–9, 1996

. 4. D. Schubert, “Refractories for Prim ary Alu m inum Production , ” pp . 74– 80 i n Proceedings of the Thirty-Seventh Symposium on Refractories, St. Louis, Missour i, March 23, 2001

. 5. J. Canon, “Alum i nu m Furnace Design: Reducti on of Metal into Metal Out Ti m e ,” pp. 237– 53 in 39th Sy mposium on Refractories, STL Section of the ACerS, April 9–10, 2003. 6. S. Quesnel, C. Allaire, and S. Afshar, “C orrosion of Refractories at the Bellyband of Alu m inum Holding and M e lting Furnac es,” pp. 321

–27 in Proceedings of the International Symposium: Advances in Refractories f o r the Metallurgical Industries II, ed. M. Rigaud and C. Allaire, Montreal, Quebec, August 4–9, 19 96

. 7. Econom ic Census 199 7 9. U.S. Enviro nm ental Protection Agenc y , Profile of the Pulp and Paper Industry, 2nd ed., EPA/310-R-9 5 -015, 2002. Available online at http ://www.epa.gov/com p liance/resources/ publications/assist ance/s e c t ors/notebooks/pulp.htm l

. 9. E. D. Larson, S. Consonni, and R. E. Katofsk y , A Cos t-Benefit Assessment of Biomass Gasification Power Generation i n the P u lp and Paper Industry, Princeton University , October 2003. Available online at http:/ /www.princet on.edu/~ener g y / publications/ pdf/20 03/BL GCC_FINAL_REPORT_8_OCT_2003

. pdf. 10. Glass: A Cle a r Vision for a Bright Future, U.S. Departm e nt of Energ y , Office of Industrial Technologies, 1996. Avail a ble online at http://www.eere.energy .gov/industr y/ glass/pdfs/glass_vision.pdf. 11. All-Electric v s . Oxyfuel Glass Melting, EPRI Technical Report TR-11278 8, El ectric Power Research Institute, April 1 999. 12. GMIC Advancing Glass M e lting Technologi es: A Technical and Econom ic Assessment. 13. Energy and E n vironmental Profile of the US Glass Industry, DOE/GO -10200 2-1 590, U.S. Department of Energ y , Off i ce of Industr ial Technolog ies, April 200 2. 14. M. J. Da m s el l, M. L. Joshi, J. R. Latter, and D. B. Wishnick, Glass Technology 37 , 1 14 (1996). 15. Personal correspondence with refr actory and glass industr y representatives. 16. ASM Heat Tr eating Society, An R&D Plan for t h e Heat Treating C o mmunity , 20 01. Available online at http://www.asm-intl.org/ pdf/RD_Plan_Heat_treat_Co mm un ity.pdf. 17. WPI Integrated Heat Tre atment Model for Alum inu mCastings, available online at http://www.wpi.edu/Academics/R e s earc h/MPI/News/ twoawards.ht ml.

48Appendix A – Referenc es

18. Steel Technology Roadm a p, Am erican Iron and Steel I n stitute, Decem b er 2001. Av ailable online at http://www.st eel.org/mt/road m ap /roadm ap.htm

. 19. Metal Castin g Industr y Pr ofile, 2004. Av ailable online at http://www.eere. energy.gov/ industr y /m e talcasting/profile.htm l. 20. Metal Castin g: Annual Re port, 2000. Available online at http://www.eere. energy.gov/ industr y /m e talcasting/annualr eport.htm l (2004 report).

49Appendix B



## Appendix B: Rotary Kiln An alysi s Schema tic, Conditions, and Results

Fig. B.1. Longitudinal section of a typical rotary kiln. Reprinted f r om Modern Refractory Practice, 3rd ed., Harbison Walker Re fractories, Pittsburgh, 1950.

Assu mptions for alumina calcination, rotary kiln Plant prod ucti on 500,00 0 tons Al 2 O 3 /year A ssu me tw o kiln s Output pe r kil n , no downtime 277,77 8 tons Al 2 O 3 /year With 90% upt ime 250,00 0 tons Al 2 O 3 /year Output pe r da y 685 ton s Al 2 O 3 /d Output pe r ho ur 29 tons Al 2 O 3 /h Kiln diameter 3.5 m (11 ft) Kiln length 80 m (26 2 ft) Kiln exterior surface 880 m 2 ( 9 46 8 ft 2 ) Rea c tion 2 Al(OH) 3 → Al 2 O 3 + 3 H 2 O Heat of rea c ti on at 77°F 634 Btu/lb Al 2 O 3 Assu me re act i on tempe r atu r e of 1100 °C 2012 °F s a y 2000 °F Heatin g pro d u cts to 20 00° F Al 2 O 3 562 Btu/lb Al 2 O 3 3 H 2 O 532 Btu/lb Al 2 O 3 Total heat re quire ment 1728 Btu/lb Al 2 O 3 3,456,82 4 Btu/ton Al 2 O 3 Heat of rea c ti on 35.91 cal/mol Rea c tion 634 64,638 Btu/# m ol Heatin g 562 Al 2 O 3 634 Btu/lb Heatin g 532 H 2 O Total 1,728 Btu/lb Al 2 O 3

50Appendix B

Results of alum ina rotary kiln an alys is (Tem peratures in °F)

Pa ram e t e r B t u /t o n % Usag e F l am e T e m p e r at ur e 36 00 Ex haus t T e m p e r at ur e 20 00 Re ac t i o n Ener g y 3, 456 ,82 4 39. 84 % W a ll L o s s Ener gy 400 ,00 0 4. 61 % Ex haus t Ener gy 4, 821 ,03 0 55. 56 % T o t a l Ener gy 8, 677 ,85 3 100. 00 % P aram et er Bt u / t o n % Us ag e F lam e T e m per at ur e 3800 E x h aus t T e m per at ur e 2000 R ea c t ion En er gy 3 , 4 56, 824 42. 46% W all Lo s s Ener gy 4 00, 000 4. 91% E x h aus t Ener gy 4 , 2 85, 360 52. 63% T ot al Ener g y 8 , 1 42, 183 1 00. 00%
Pa ram e t e r B t u /t o n % Usag e F l am e T e m p e r at ur e 36 00 Ex haus t T e m p e r at ur e 20 00 Re ac t i o n Ener g y 3, 456 ,82 4 37. 87 % W a ll L o s s Ener gy 600 ,00 0 6. 57 % Ex haus t Ener gy 5, 071 ,03 0 55. 56 % T o t a l Ener gy 9, 127 ,85 3 100. 00 % P aram et er Bt u / t o n % Us ag e F lam e T e m per at ur e 3800 E x h aus t T e m per at ur e 2000 R ea c t ion En er gy 3 , 4 56, 824 40. 36% W all Lo s s Ener gy 6 00, 000 7. 01% E x h aus t Ener gy 4 , 5 07, 582 52. 63% T ot al Ener g y 8 , 5 64, 406 1 00. 00%
Pa ram e t e r B t u /t o n % Usag e F l am e T e m p e r at ur e 36 00 Ex haus t T e m p e r at ur e 18 00 Re ac t i o n Ener g y 3, 456 ,82 4 44. 81 % W a ll L o s s Ener gy 400 ,00 0 5. 19 % Ex haus t Ener gy 3, 856 ,82 4 50. 00 % T o t a l Ener gy 7, 713 ,64 7 100. 00 % P aram et er Bt u / t o n % Us ag e F lam e T e m per at ur e 3800 E x h aus t T e m per at ur e 1800 R ea c t ion En er gy 3 , 4 56, 824 47. 17% W all Lo s s Ener gy 4 00, 000 5. 46% E x h aus t Ener gy 3 , 4 71, 141 47. 37% T ot al Ener g y 7 , 3 27, 965 1 00. 00%
Pa ram e t e r B t u /t o n % Usag e F l am e T e m p e r at ur e 36 00 Ex haus t T e m p e r at ur e 18 00 Re ac t i o n Ener g y 3, 456 ,82 4 42. 61 % W a ll L o s s Ener gy 600 ,00 0 7. 39 % Ex haus t Ener gy 4, 056 ,82 4 50. 00 % T o t a l Ener gy 8, 113 ,64 7 100. 00 % P aram et er Bt u / t o n % Us ag e F lam e T e m per at ur e 3800 E x h aus t T e m per at ur e 1800 R ea c t ion En er gy 3 , 4 56, 824 44. 85% W all Lo s s Ener gy 6 00, 000 7. 78% E x h aus t Ener gy 3 , 6 51, 141 47. 37% T ot al Ener g y 7 , 7 07, 965 1 00. 00%

Savings for alumina Btu/ton N a tu r e of s avin g sav ed Effec tof 200 ° F increa se in flame temperature 472,62 1 Effec tof 200 ° F decrea s e in exhaust tem peratu r e 912,26 8 Effect of redu cing wall lo ss energy from 600,00 0 to 400,00 0 Btu/ton 413,05 6

51Appendix B

Assu mptions for lime calc ination, rotary kiln Plant prod ucti on 730,00 0 tons CaO/yea r A ssu me tw o kiln s Output pe r kil n , no downtim e 405,55 6 tons CaO /yea r With 90% upt ime 365,00 0 tons CaO /yea r Output pe r da y 1,000 ton s CaO /d Output pe r ho ur 42 tons CaO /h Kiln diameter 5 m (16 ft) Kiln length 50 m (16 4 ft) Kiln exterior surface 785 m 2 (8,454 ft 2 ) Rea c tion Ca CO 3 → Ca O + CO 2 Heat of rea c ti on at 77°F 1364 Btu/lb CaO Assu me re act i on tempe r atu r e of 1000 °C 1832 °F s a y 1800 °F Heatin g pro d u cts to 18 00° F CaO 371 Btu/lb Ca O CO 2 391 Total heat re quire ment 2126 Btu/lb CaO 4,252,25 9 Btu/ton CaO Heat of rea c ti on 57.29 cal/mol Rea c tion 1364 103,12 2 Btu/#mol Heatin g 417 CaO 1,839 Btu/lb Heatin g 415 CO 2 Total 2,196 Btu/lb CaO

52Appendix B

Results of li me rotary kiln analysis (neglecting dust loss) (Tem peratures in °F)

Param e t e r B t u / t o n % Us ag e Fla m e T e m p er atu r e 36 00 E x h a u s t T e m p e r ature 20 00 Rea c tio n En er gy 4 , 25 2, 25 9 4 0.6 2 % W a ll Lo s s En er gy 40 0,0 0 0 3 .8 2% Ex ha us tEne r g y 5 , 81 5, 32 3 5 5.5 6 % T o tal Ene r gy 1 0 ,4 67 ,58 2 10 0.0 0 % P aram e t e r Bt u /t o n % U s a g e F la m e T e m p er atu r e 3 800 E xh au st T e m p e r ature 2 000 R ea c t io n En er gy 4,2 5 2 , 2 5 9 43. 30 % W a ll Lo s s En er gy 40 0, 00 0 4

. 0 7 % E x h a u s tEne r g y 5,1 6 9 , 1 7 6 52. 63 % T o t al Ene r gy 9,8 2 1 , 4 3 5 1 00. 00 %
Param e t e r B t u / t o n % Us ag e Fla m e T e m p er atu r e 36 00 E x h a u s t T e m p e r ature 20 00 Rea c tio n En er gy 4 , 25 2, 25 9 3 8.9 5 % W a ll Lo s s En er gy 60 0,0 0 0 5 .5 0% Ex ha us tEne r g y 6 , 06 5, 32 3 5 5.5 6 % T o tal Ene r gy 1 0 ,9 17 ,58 2 10 0.0 0 % P aram e t e r Bt u /t o n % U s a g e F la m e T e m p er atu r e 3 800 E xh au st T e m p e r ature 2 000 R ea c t io n En er gy 4,2 5 2 , 2 5 9 41. 51 % W a ll Lo s s En er gy 60 0, 00 0 5

. 8 6 % E x h a u s tEne r g y 5,3 9 1 , 3 9 9 52. 63 % T o t al Ene r gy 10, 24 3,6 5 7 1 00. 00 %
Param e t e r B t u / t o n % Us ag e Fla m e T e m p er atu r e 36 00 E x h a u s t T e m p e r ature 18 00 Rea c tio n En er gy 4 , 25 2, 25 9 4 5.7 0 % W a ll Lo s s En er gy 40 0,0 0 0 4 .3 0% Ex ha us tEne r g y 4 , 65 2, 25 9 5 0.0 0 % T o tal Ene r gy 9 , 30 4, 51 7 1 0 0 .0 0% P aram e t e r Bt u /t o n % U s a g e F la m e T e m p er atu r e 3 800 E xh au st T e m p e r ature 1 800 R ea c t io n En er gy 4,2 5 2 , 2 5 9 48. 11 % W a ll Lo s s En er gy 40 0, 00 0 4

. 5 3 % E x h a u s tEne r g y 4,1 8 7 , 0 3 3 47. 37 % T o tal Ene r gy 8,8 3 9 , 2 9 1 1 00. 00 %
Param e t e r B t u / t o n % Us ag e Fla m e T e m p er atu r e 36 00 E x h a u s t T e m p e r ature 18 00 Rea c tio n En er gy 4 , 25 2, 25 9 4 3.8 2 % W a ll Lo s s En er gy 60 0,0 0 0 6 .1 8% Ex ha us tEne r g y 4 , 85 2, 25 9 5 0.0 0 % T o tal Ene r gy 9 , 70 4, 51 7 1 0 0 .0 0% P aram e t e r Bt u /t o n % U s a g e F la m e T e m p er atu r e 3 800 E xh au st T e m p e r ature 1 800 R ea c t io n En er gy 4,2 5 2 , 2 5 9 46. 12 % W a ll Lo s s En er gy 60 0, 00 0 6

. 5 1 % E x h a u s tEne r g y 4,3 6 7 , 0 3 3 47. 37 % T o tal Ene r gy 9,2 1 9 , 2 9 1 1 00. 00 %

Savings for lime, neglecti n g dust loss Btu/ton N a tu r e of s avin g sav ed Effec tof 200 ° F increa se in flame temperature 567,63 1 Effec tof 200 ° F decrea s e in exhaust tem peratu r e 1,095,66 0 Effect of redu cing wall lo ss energy from 600,00 0 to 400,00 0 Btu/ton 413,05 6

53Appendix B

Results of li me rotary kiln analysis (assuming 20% dust loss) (Tem peratures in °F)

P a ra meter Btu/t on % Usa g e F l am e T e m p er atu r e 36 00 Ex h a u s t T e m p er at ur e 20 00 Re actio n Ene r gy 5 , 1 0 2 , 7 1 0 3 9

. 00% W a ll L o s s En e r gy 40 0, 00 0 3 .0 6 % Exha ust En ergy 7 , 5 8 1 , 7 6 7 5 7

. 94% T o tal Ene r g y 13,08 4,47 8 100 .00% P a r a m ete r B t u/ton % Usa g e F l a m e T e m p er a t u r e 38 00 E x h au s tT e m p er atu r e 2 0 0 0 Reactio n En ergy 5,1 02,7 1 0 4 3.30 % W a l l L o s s En er gy 40 0 , 00 0 3 .3 9% Exha ust E nerg y 6,2 83,0 1 2 5 3.31 % T o tal Ene r gy 1 1 ,78 5 ,72 2 10 0.00 %
P a ra meter Btu/t on % Usa g e F l am e T e m p er atu r e 36 00 Ex h a u s t T e m p er at ur e 20 00 Re actio n Ene r gy 5 , 1 0 2 , 7 1 0 3 7

. 39% W a ll L o s s En e r gy 60 0, 00 0 4 .4 0 % Exha ust En ergy 7 , 9 4 4 , 2 6 7 5 8

. 21% T o tal Ene r g y 13,64 6,97 8 100 .00% P a r a m ete r B t u/ton % Usa g e F l a m e T e m p er a t u r e 3 8 0 0 E x h au s tT e m p er atu r e 2 0 0 0 Reactio n En ergy 5,1 02,7 1 0 4 1.51 % W a l l L o s s En er gy 60 0 , 00 0 4 .8 8% Exha ust E nerg y 6,5 89,6 7 8 5 3.61 % T o tal Ene r gy 1 2 ,29 2 ,38 9 10 0.00 %
P a ra meter Btu/t on % Usa g e F l am e T e m p er atu r e 36 00 Ex h a u s t T e m p er at ur e 18 00 Re actio n Ene r gy 5 , 1 0 2 , 7 1 0 4 3

. 87% W a ll L o s s En e r gy 40 0, 00 0 3 .4 4 % Exha ust En ergy 6 , 1 2 7 , 9 3 6 5 2

. 69% T o tal Ene r g y 11,63 0,64 7 100 .00% P a r a m ete r B t u/ton % Usa g e F l a m e T e m p er a t u r e 3 8 0 0 E x h au s tT e m p er atu r e 1 8 0 0 Reactio n En ergy 5,1 02,7 1 0 4 8.11 % W a l l L o s s En er gy 40 0 , 00 0 3 .7 7% Exha ust E nerg y 5,1 04,4 3 9 4 8.12 % T o tal Ene r gy 1 0 ,60 7 ,15 0 10 0.00 %
P a ra meter Btu/t on % Usa g e F l am e T e m p er atu r e 36 00 Ex h a u s t T e m p er at ur e 18 00 Re actio n Ene r gy 5 , 1 0 2 , 7 1 0 3 7

. 39% W a ll L o s s En e r gy 60 0, 00 0 4 .4 0 % Exha ust En ergy 7 , 9 4 4 , 2 6 7 5 8

. 21% T o tal Ene r g y 13,64 6,97 8 100 .00% P a r a m ete r B t u/ton % Usa g e F l a m e T e m p er a t u r e 3 8 0 0 E x h au s tT e m p er atu r e 1 8 0 0 Reactio n En ergy 5,1 02,7 1 0 4 6.12 % W a l l L o s s En er gy 60 0 , 00 0 5 .4 2% Exha ust E nerg y 5,3 60,4 3 9 4 8.45 % T o tal Ene r gy 1 1 ,06 3 ,15 0 10 0.00 %

Savings for lime, assu min g dust loss Btu/ton N a tu r e of s avin g sav ed Effec tof 200 ° F increa se in flame temperature 1,565,16 7 Effec tof 200 ° F decrea s e in exhaust tem peratu r e 965,41 0 Effect of redu cing wall lo ss energy from 600,00 0 to 400,00 0 Btu/ton 885,37 4

5455Appendix C



## Appendix C: Reverberatory Furnace Schematics

Fig. C.1. Reverberatory f u rnace sch e m atic.

56Appendix C

Fig. C.2. Typical reverbe r atory aluminum-melting furnace. Reprinted from Modern Refractory Practice, 3rd ed., Harbison Walker Refractories, Pittsburgh, 1950.

57Appendix D



## Appendix D: Reverb erat ory Furn ace Anal ysis Con d itions and Results

Results of aluminum re verb erator yfurnace analysis Temperature (oF) Wa ll/ro o f L o ss Case Flame Exhaust (Btu/h ) C a se 1 36 0 0 16 0 0 5, 00 0, 0 00 C a se 2 38 0 0 16 0 0 5, 00 0, 0 00 C a se 3 36 0 0 16 0 0 7, 50 0, 0 00 C a se 4 38 0 0 16 0 0 7, 50 0, 0 00 C a se 5 36 0 0 18 0 0 5, 00 0, 0 00 C a se 6 38 0 0 18 0 0 5, 00 0, 0 00 C a se 7 38 0 0 16 0 0 7, 50 0, 0 00 C a se 8 38 0 0 18 0 0 7, 50 0, 0 00
Results of aluminum r e verberatory f u rnace analysis (Tem peratures in °F) Cas e 1 Par a m e t e r Bt u / h % U sag e Fla m e T e m p e r atur e 3600 Ex h aus tT e m p e r atu r e 1600 Me lting Ener gy 10, 095, 271 37. 2% W a ll Los s En er gy 5, 000, 000 18. 4% Ex h aus tEner g y 12, 076, 217 44. 4% T o t a l Ener g y 27, 171, 489 1 00. 0% Cas e 3 Par a m e t e r Bt u / h % U sag e Fla m e T e m p e r atur e 3600 Ex h aus tT e m p e r atu r e 1600 Me lting Ener g y 10, 095, 271 31. 9% W a ll Los s En er gy 7, 500, 000 23. 7% Ex h aus tEner g y 14, 076, 217 44. 4% T o t a l Ener g y 31, 671, 489 1 00. 0% Cas e 5 Par a m e t e r Bt u / h % U sag e Fla m e T e m p e r atur e 3600 Ex h aus tT e m p e r atu r e 1800 Me lting Ener gy 10, 095, 271 33. 4% W a ll Los s En er gy 5, 000, 000 16. 6% Ex h aus tEner g y 15, 095, 271 50. 0% T o t a l Ener g y 30, 190, 543 1 00. 0% Cas e 7 Par a m e t e r Bt u / h % U sag e Fla m e T e m p e r atur e 3600 Ex h aus tT e m p e r atu r e 1800 Me lting Ener gy 10, 095, 271 28. 7% W a ll Los s En er gy 7, 500, 000 21. 3% Ex h aus tEner g y 17, 595, 271 50. 0% T o t a l Ener g y 35, 190, 543 1 00. 0% C as e 2 P ar a m et e r Btu/ h % Us a g e F lam e T e m per at ur e 380 0 E x hau s t T e m per at ur e 160 0 Melt ing Ener gy 1 0 ,0 95, 271 3 8

. 7 % W a ll Los s Ener g y 5,0 00, 000 1 9

. 2 % Ex hau s tEner gy 1 0 ,9 78, 379 4 2

. 1 % T o ta l Ener gy 2 6 ,0 73, 651 1 0 0

. 0 % C as e 4 P ar a m et e r Btu/ h % Us a g e F lam e T e m per at ur e 380 0 E x hau s t T e m per at ur e 160 0 Melt ing Ener g y 1 0 ,0 95, 271 33 .2% W a ll Los s Ener g y 7,5 00, 000 2 4

. 7 % Ex hau s tEner gy 1 2 ,7 96, 561 4 2

. 1 % T o ta l Ener gy 3 0 ,3 91, 833 1 0 0

. 0 % C as e 6 P ar a m et e r Btu/ h % Us a g e F lam e T e m per at ur e 380 0 E x hau s t T e m per at ur e 180 0 Melt ing Ener gy 1 0 ,0 95, 271 3 5

. 2 % W a ll Los s Ener g y 5,0 00, 000 1 7

. 4 % Ex hau s tEner gy 1 3 ,5 85, 744 4 7

. 4 % T o ta l Ener gy 2 8 ,6 81, 016 1 0 0

. 0 % C as e 8 P ar a m et e r Btu/ h % Us a g e F lam e T e m per at ur e 380 0 E x hau s t T e m per at ur e 180 0 Melt ing Ener gy 1 0 ,0 95, 271 3 0

. 2 % W a ll Los s Ener g y 7,5 00, 000 2 2

. 4 % Ex hau s tEner gy 1 5 ,8 35, 744 4 7

. 4 % T o ta l Ener gy 3 3 ,4 31, 016 1 0 0

. 0 %

58Appendix D

Savings for aluminum r e verberatory f u rnaces
Furnac e cha nge Btu/h sav ed Btu/lb Al sav ed Effec tof 200 ° F increa se in flame temperature 1,411,63 7 70.58 Effec tof 200 ° F decrea s e in exhaust tem peratu r e 3,486,04 6 174.30 Effect of redu cing wall lo ss energy from 7.5 to 5 million 4,642,04 5 232.10

Cas e 1 Par a m e t e r Bt u / h % U sag e Fla m e T e m p e r atur e 3600 Ex h aus tT e m p e r atu r e 2200 Me lting Ener gy 6, 272, 301 21. 6% W a ll Los s En er gy 5, 000, 000 17. 2% Ex h aus tEner g y 17, 713, 616 61. 1% T o t a l Ener g y 28, 985, 917 1 00. 0% Cas e 3 Par a m e t e r Bt u / h % U sag e Fla m e T e m p e r atur e 3600 Ex h aus tT e m p e r atu r e 2200 Me lting Ener gy 6, 272, 301 17. 7% W a ll Los s En er gy 7, 500, 000 21. 2% Ex h aus tEner g y 21, 642, 188 61. 1% T o t a l Ener g y 35, 414, 489 1 00. 0% Cas e 5 Par a m e t e r Bt u / h % U sag e Fla m e T e m p e r atur e 3600 Ex h aus tT e m p e r atu r e 2400 Me lting Ener gy 6, 272, 301 18. 5% W a ll Los s En er gy 5, 000, 000 14. 8% Ex h aus tEner g y 22, 544, 602 66. 7% T o t a l Ener g y 33, 816, 904 1 00. 0% Cas e 7 Par a m e t e r Bt u / h % U sag e Fla m e T e m p e r atur e 3600 Ex h aus tT e m p e r atu r e 2400 Me lting Ener gy 10, 095, 271 24. 4% W a ll Los s En er gy 7, 500, 000 18. 2% Ex h aus tEner g y 23, 721, 632 57. 4% T o t a l Ener g y 41, 316, 904 1 00. 0% Results of co pper reve r be ratory furnace analysis (Tem peratures in °F)

Savings for c o pper rev erb eratory furnaces C as e 2 P ar a m et e r Btu/ h % Us a g e F lam e T e m per at ur e 380 0 E x hau s t T e m per at ur e 220 0 Melt ing Ener gy 6,2 72, 301 2 3

. 4 % W a ll Los s Ener g y 5,0 00, 000 1 8

. 7 % Ex hau s tEner gy 1 5 ,4 99, 414 5 7

. 9 % T o ta l Ener gy 2 6 ,7 71, 715 1 0 0

. 0 % C as e 4 P ar a m et e r Btu/ h % Us a g e F lam e T e m per at ur e 380 0 E x hau s t T e m per at ur e 220 0 Melt ing Ener gy 6,2 72, 301 1 9

. 2 % W a ll Los s Ener g y 7,5 00, 000 2 2

. 9 % Ex hau s tEner gy 1 8 ,9 36, 914 5 7

. 9 % T o ta l Ener gy 3 2 ,7 09, 215 1 0 0

. 0 % C as e 6 P ar a m et e r Btu/ h % Us a g e F lam e T e m per at ur e 380 0 E x hau s t T e m per at ur e 240 0 Melt ing Ener gy 6,2 72, 301 2 0

. 5 % W a ll Los s Ener g y 5,0 00, 000 1 6

. 3 % Ex hau s tEner gy 1 9 ,3 23, 945 6 3

. 2 % T o ta l Ener gy 3 0 ,5 96, 246 1 0 0

. 0 % C as e 8 P ar a m et e r Btu/ h % Us a g e F lam e T e m per at ur e 380 0 E x hau s t T e m per at ur e 240 0 Melt ing Ener gy 6,2 72, 301 1 6

. 8 % W a ll Los s Ener g y 7,5 00, 000 2 0

. 1 % Ex hau s tEner gy 2 3 ,6 09, 659 6 3

. 2 % T o ta l Ener gy 3 7 ,3 81, 960 1 0 0

. 0 %

Furnac e cha nge Btu/h sav ed Btu/lb Al sav ed Effec tof 200 ° F increa se in flame temperature 3,018,769 150.94 Effec tof 200 ° F decrea s e in exhaust tem peratu r e 5,791,405 289.57 Effect of redu cing wall lo ss energy fr om 7.5 to 5 million 6,662,946 333.15

59Appendix D

Results of glass reverb er atory furnace analysis (Tem peratures in °F)

Cas e 1 Par a m e t e r Bt u / h % U sag e Fla m e T e m p e r atur e 3600 Ex h aus tT e m p e r atu r e 2800 Me lting Ener gy 13, 771, 643 16. 3% W a ll Los s En er gy 5, 000, 000 5. 9% Ex h aus tEner g y 65, 700, 751 77. 8% T o t a l Ener g y 84, 472, 394 1 00. 0% Cas e 3 Par a m e t e r Bt u / h % U sag e Fla m e T e m p e r atur e 3600 Ex h aus tT e m p e r atu r e 2800 Me lting Ener gy 13, 771, 643 14. 4% W a ll Los s En er gy 7, 500, 000 7. 8% Ex h aus tEner g y 74, 450, 751 77. 8% T o t a l Ener g y 95, 722, 394 1 00. 0% Cas e 5 Par a m e t e r Bt u / h % U sag e Fla m e T e m p e r atur e 3600 Ex h aus tT e m p e r atu r e 3000 Me lting Ener gy 13, 771, 643 12. 2% W a ll Los s En er gy 5, 000, 000 4. 4% Ex h aus tEner g y 93, 858, 216 83. 3% T o t a l Ener g y 112, 629, 859 1 00. 0% Cas e 7 Par a m e t e r Bt u / h % U sag e Fla m e T e m p e r atur e 3600 Ex h aus tT e m p e r atu r e 3000 Me lting Ener gy 13, 771, 643 10. 8% W a ll Los s En er gy 7, 500, 000 5. 9% Ex h aus tEner g y 106, 358, 216 83. 3% T o t a l Ener g y 127, 629, 859 1 00. 0% C as e 2 P ar a m et e r Btu/ h % Us a g e F lam e T e m per at ur e 380 0 E x hau s t T e m per at ur e 280 0 Melt ing Ener gy 1 3 ,7 71, 643 1 9

. 3 % W a ll Los s Ener g y 5,0 00, 000 7. 0 % Ex hau s tEner gy 5 2 ,5 60, 601 7 3

. 7 % T o ta l Ener gy 7 1 ,3 32, 244 1 0 0

. 0 % C as e 4 P ar a m et e r Btu/ h % Us a g e F lam e T e m per at ur e 380 0 E x hau s t T e m per at ur e 280 0 Melt ing Ener gy 1 3 ,7 71, 643 1 7

. 0 % W a ll Los s Ener g y 7,5 00, 000 9. 3 % Ex hau s tEner gy 5 9 ,5 60, 601 7 3

. 7 % T o ta l Ener gy 8 0 ,8 32, 244 1 0 0

. 0 % C as e 6 P ar a m et e r Btu/ h % Us a g e F lam e T e m per at ur e 380 0 E x hau s t T e m per at ur e 300 0 Melt ing Ener gy 1 3 ,7 71, 643 1 5

. 4 % W a ll Los s Ener g y 5,0 00, 000 5. 6 % Ex hau s tEner gy 7 0 ,3 93, 662 7 8

. 9 % T o ta l Ener gy 8 9 ,1 65, 305 1 0 0

. 0 % C as e 8 P ar a m et e r Btu/ h % Us a g e F lam e T e m per at ur e 380 0 E x hau s t T e m per at ur e 300 0 Melt ing Ener gy 1 3 ,7 71, 643 1 3

. 6 % W a ll Los s Ener g y 7,5 00, 000 7. 4 % Ex hau s tEner gy 7 9 ,7 68, 662 7 8

. 9 % T o ta l Ener gy 10 1,0 40, 305 100 .0%
Savings for glass reverb er atory furnaces

Furnac e cha nge Btu/h sav ed Btu/lb glass sav ed Effec tof 200 ° F increa se in flame temperature 19,521,1 02 976.06 Effec tof 200 ° F decrea s e in exhaust tem peratu r e 31,173,9 01 1,558.70 Effect of redu cing wall lo ss energy from 7.5 to 5 million 11,906,2 50 595.31

6061Appendix E



## Appendix E: Boiler Schematic

Fig. E.1. Boiler furnace s e ctions. Reprinted from Mo dern Refractory Practic e, 3rd ed., Harbison Walker Refractori es, Pittsburgh, 1950.

6263