Embed Size (px)
Citation preview
"Reprinted from COAL, Kural,O.,ed., IstanbulTech. Univ., I'99'i p. 253-269"
Mehmef Sabri CELlKIstanbul Technical University, Istanbul. Tiirkiye
P. SOMASUNDARANColumbia University, New York, USA
20.1 INTRODUCTION
Coal is a complex and heterogeneous materialcomprised of a variety of organic andinorganic constituents in different forms.While silicates and carbonates constitute themajor ash-forming minerals. the principal
sulphur-bearing minerals in coal are pyrite andmarcasite. Other sulphide minerals, e.g..elemental sulphur. calcium and iron sulphates,are found in minor quantities. A considerablePOrtion of the sulphur Content may be organic
in the form of alkyl and aryl thiols. sulphides.
and disulphides and as heterocycliccompounds of the thiophene type (Wheelockand Markuszewski, 198 I ; Stock. 1989). Inbituminous coals, the thiophene type forms 40-70% of the organic sulphur. whereas the reSt iscomposed of aromatic. cyclic and aliphaticsulphur compounds in different proportionsdepending upon the coal rank. Organic sulphurlevels in coal COmmonly range from about0.3% to Over 2.0%. whereas the pyritic sulphurContent may vary from 0.1 % to 4.0%.Hovewer. in some unusual Cases the organicsulphur levels may be as high as 10% withsulphate contents up to I %. Pyrite may bepresent in a wide variety of forms rangingfrom large balls to micron and sub-micron sizeframboids.
precombustion coal cleaningrecovery of sulphur oxides duringcombustionpostcombustion scrubbers andprecipitators
= ~ -= - --~--
-==
2S4 COAL
, .methods includes removal of the organicsulphur as well. A schematic illustration of theexisting and novel precombustion techniquesfor coal desulphurization is given in Figure20.1.
Double Stroke Pulsation Jigs are reported toperform well in the desulphurization of minus2 rnrn coal (Breuer and Jungmann. 1986).
20.2.1 Physical Cleaning Methods
Physical cleaning methods 'are highlysuccessful in removing the large fragments ofassociated minerals but fail in effectivelyremoving die finer panicles (-0.1 mm) in coal.However, novel technologies are beingdeveloped which show promise for removingthe finer mineral fractions of coal as well.Constituents chemically bound to coal matrixsuch as organic sulphur cannot be separated byphysical methods.
.-.
Reduction of the sulphur content of 'coaldepends upon the coal rank, liberation size, theoriginal sulphur, content, and thepy-"ticlorganic sulphur ratio. Coal can becleaned to a desired level by adjusting the sizedistribution and the effecti ve separationdensity in the cleaning process at the expenseof coal recoveries.
About 25-30% of coarse coals are cleaned byheavy media separation circuits. Heavymedium processing is primarily effective onthe coarser fractions of coal. However, densemedium cyclones can treat coals down to 0.1mm at gravities as low as 1.3 (Matoney el aI..1988). The substitution of centrifugal force for
Jo. gravitational force allows increasingly finer
sizes to be processed. As the size of theparticles approaches the size of the magnetiteparticles (-325 mesh) used to formulate thedense medium, an effective separation can nolonger be made. Therefore. there is a growinginterest in replacing the magnetite-water
; medium with heavy liquids such as Freon 113
and methylene chloride. Among densemedium cyclones. Vorsyl, Larcodems.DynawhirJpool and Tri-FJo systems aresuitable for relatively medium sized coals(Shah el al.. 1982; Cammock, 1987; Brookesand Miles. 1987; Kolb and Steiner. 1986).
The perfonnance of Humphrey Spiral andReichert Cones appears to be optimum over arelatively wide size range from 3 to 0.1 min.Spirals are gradually replacing hydrocyclones,finecs>al jigs and coarse froth flotation due tohigher yields, lower ash and pyritic sulphur inthe cleaned product and ease of operation andmaintenance. Spirals !!fe particularly popularin the Republic of South Africa and Australia(Horsfall, 1988; Brookes and Miles, 1987;'Gallagher et al., 1986; A~k et aI., 1993).
Comminution machines developed for coalshould ideally break along the grainboundaries separating the organic and theinorganic constituents. Chemical comminutionusing additives such as anhydrous ammonia.which adsorbs on coal but is not receptive toinorganic phases, is claimed to liberate coalalong the interfacial boundaries (Howard andDatta, 1977). . .
20.2.1.1 Gravity Based SeparationsWater-only-cyclones (hydrocyclones) which
The most widely used separation device to can treat 0.5xO.15 mm fractions areclean medium sized coal is the coal jig. About chara~terized by simple design. a low35-40% of the total coal washed is processed cost/hlgh capacity ratio and the ability to cleanby jigs. The Baum Type and its newer without using an artificial heavy medium. The~ersions. Batac and Feldspar Jigs have prob~ems. of these devices are the lack ofIncreased the capacity and efficiency- of the efficIency and the need for large amounts of
.jigging processs for fine coal (-10 mm) and water. They are generally used as primarycoarse coal (150-200 mm). Ba.tac Jigs in the cleaning devices for cleaning raw coal (20 xHomer City Coal Preparation Plant reportedly 0.15~) at! ~'!: 1.9 specific gravitiesproduce a low-ash low-sulphur product (Schl~~~f1ffi~88; .wills, 1985).
.;-.Jb~c."'l~_~~y('JQnecL - ---~ ~ ~~
- --!- ~
=-,:-c_'
256 COAl-~~,.
.J ,"Wet shaking tables can process particles m the 20.2.1.2 Separations Based on Surfacesize range of 8xO.15 mm and can be inStalled Propertiesat up to four-stacked tables. The tables cantreat coal only in certain specific gravity Flotation is a promising method for se~tingfractions. In China, centrifugal tables with pyrite from coal. There has been an upsurge ofcylindrical surfaces have enabled the interest in developing both processing andprocessing of very fine particles (-0.04 mm) reagent strategies to desulphurize cmJ byand the removal of 55-77% of the...' pyritic flotation. The problem arises partly fromsulphur from coal (Fan et al., 1982). The use similarities in the surface properties ofof pneumatic tables (air tables) appears to have unweathered coal and fresh coal pyritedeclined in recent years. Mozley's Multi contaminated with hydrocarbons, Other ...~~~Gravity Separator (Figure 20.2), which is problems include the incomplete liber3lion of .based on the action of a shaking table, has pyrite from coal, recovery of pyrite by +extended the size range of tables to sub-sieve hydraulic entrainment, hydrophobization ofsize range and is reported to perform well in pyrite by superficial oxidation, andthe separation of pyritic sulphur. hydrophobic interaction between pyrite and
flotation reagents (Yoon et al., 1991).
~- - 4-6 ~ Depressants are the major class of flotationAmpIitu~ ~-20~~ reagents extensively studied f<.- the ~
/:: C= desulphurization of coal beacause of their :r=',oIatiof\~ /~:=.~ ~~~=::.- potential in depressing pyrite. These .."",~~t"~-2"rpm ~~~L~_~ \1 riI _iC depressants incl~de hydrolyzed metal ions ..-'.-4-:
(Baker and Miller, 1971), starches and "1~ polysaccharides (1m and Aplan, 1981; Perry ;
and Aplan, 1985), poly xanthate (Attia et al., !1988), oxidizing and reducing agents (Celik :and Somasundaran, 1980), anionic andcationic surfactants partially as collectors(Read et al., 1989; Stonestreet and Franzidis,1988) arid--quinonoid compounds which showsuperior performance over the co~rcially
~ --- available sulphur-based depressants (Celik et(0..- FnxtionI 0'-" ~ F~ (II., 1990). Howevert-:- every effective
. depressant developed so far either depresses
.. coal or requires prohibitively large reagent.. dosages (Aplan, 1993). It may still be possible,
however, to tailor a suitable depressant for aparticular coal.
~~~~~~~~
,.
~~~~
Figure 20.2 Laboratory or pilot plant version ofmultigravity separator.
The Air Sparged Hydrocyclones (ASH) havebeen designed to improve the efficiency of Processing strategies include the two-stagewater-only-cyclones. The ASH was developed reverse flotation process. the grab and runfor fast and efficient flotation separation of approach, and new cell designs such asfine particles, particularly those of pyrit(;, in a microbubble column. The two-stage reversecentrifugal field. The slurry is fed tangentjally flotation process, developed by USBM. uses .t~ough the conventional cyclone header to combination of both reagent and processdevelop a swirl flow thus shearing the air to strategies (Miller and Deurbrouck. 1978). Coal i
produce a high concentration of small bubbles is floated in the first stal!e and subsequently ~!which act in a manner similar to those in - depressed ~e~ond~(age-by polymeric. ~;flotation (Miller et al.. 1988). ~~~~~~~illcess bas ~~~~~-J:ItO:1 I-
;
-- - --- - .j
iron pentacarbonyl at 170°C and microwaveenergy. Lua and Boucher (1990) reportedpyritic sulphur reductions of 99% on apulverized bituminous coal in the size range ofminus 0.1 rom. The use of alkaline extractionunder pressure has been shown to increase themagnetic susceptibility of pyrite over coal andin turn, facilitate the separation of pyrite byhigh gradient magnetic separation (Hall andFinch, 1984.). Desulphurization of lignites byhigh gradient magnetic separation has beenattempted with success (Ozbayoglu, 1986).
1986). Studies on thennophilic pyriteoxidizing bacteria such as Sulpholobus havealso been reported (Gokcay and Yurteri, 1983:Kargi and Robinson, 1982). Bioprocessvariables involved in microbial pyrite removalare given in Figure 20.4 (Olson andBrinckrnan, 1986).
PHYSICAL
temperatu~particle s~\concentrationpressure i
CHEMICAL
/ ~trients" t~xicontsgasespH
The separation of materials in the electrostaticprocess is based on the differences in one ormore of their electrical properties such as thedielectric constant, electrical conductivity, andwork function. The TriboelectrostaticSeparation process relies on selectively,placing positive charges on coal and negativecharges on the associated matter, includingpyrite (Hucko et al., 1988; Mills and Cheng,1993).
BIOLOGICALocganism interactionmetal resistanceinoculum sizestrain characteristics
Figure 20.4 Bioprocess variables in pyriteremoval (Olson and Brinckman. 1986).
20.2.2 Microbial CleaningA breakthrough has reportedly been achievedby the Atlantic Research Corporation whichhas developed a new strain, CBl (Coal Bug 1,a mutant of pseudomonas); this microbeproduces enzymes to oxidize the sulphur inthiophcnic groups. The same research groupalso patented CB2, a member of the genusAcinetobacter, which is claimed to attack thediphenylsulphide fonI).of the organic sulphur.Isbister et aI. (1986) reports an average of37% removal of organic sulphur from Illinoisand Homer City coals by CB I.
Microbial beneficiation is capable of removingboth organic and inorganic sulphur atrelatively moderate temperature and pressure.Bacterial removal has been pursued in twoways: (I') bacterial leaching, and (il') bacterialconditioning followed by flotation (Dogan andCelik, 1992; Dogan and Ozbayoglu, 1985).
The mechanism of oxidation of pyrite byThiobacillus type bacteria has been ascribed to,the fonnation of soluble species such as ferricsulphate and sui ph uric acid as below:
The conditioning of coal by bacteria followedby flotation or oil agglomerdtion has markedlylowered the conditioning time required tominutes and improved the removal of ash andpyritic sulphur (Capes et al.. 1973; Kemptonet al.. 1980; EI-Zeky and Attia. 1987). Forinstance. Dogan ( 1990) reports that whilebacterial leaching of a Turkish lignite required10 days. bacterial conditioning followed byflotation required only four hours andproduceda.superior~ coa~-~ompared to thatproduced by the bacterial leaching alone.
4 FeS2 + 1502 +2H2O= 2Fe2(S04h + 2 H2SO4
(20.1)The bulk of the research on sulphur removalby microbial methods has involved theoxidation of pyrite by bacteria such asThiobacillus ferrooxidans to form water-soluble iron sulphate. The removal of pyriticsulphur from coal has been reported in thiscase to be as high as 97% (Gullu et al., 1992;Dugan and Apel, 1978; Detz and Barvinchak~1979; Bos et al.. 1986; Torma and Gundiler,
:w,,*.~
~
sulphur compounds are decomposed atrelatively lower temperatures, thiophenesdecompose only above 800°C (Calkins, 1987).Coal pyrite, as opposed to mineral pyrite, isreduced by hydrogen to H2S at temperatures aslow as 250°C. Pyrite in the presence of an
oxidizing agent undergoes reactions at 350-400°C and is converted to water solublesulphates (Sinha and Walker, 1972).
this fonns the basis of the Meyers Process(Meyers, 1977). Nitrogen oxide is alSi) used toremove pyritic sulphur in two steps ~Ilowedby hot caustic treatment to remQ:'Ct' someportion of the organic sulphur. Nitlic acid,ozone and hydrogen peroxide (Whedbck andMarkuszewski, 1981) and bromine '~chuctzand Serrini, 1988) have also been testat. for theremoval of sulphur from coal.
Caustic Treatments: Heating of an aqueousslurry of powdered coal in the premtce of10% NaOH and 2-3% Ca(OH)2 at a:.300°Cfor 10-30 minute is employed in the BatelleHydrothermal Process. Over 90% of thepyritic and 50% of the organic sulphur'can beremoved by this processs. The application ofmicrowave irradiation on caustic treaed anddewatered coal has been shown to remove90% of the pyritic and 50-70% of the organicsulphur from coal (Zavitsano et al., 1978).
The Molten-Caustic-Leaching Process (MLC),commonly known as the TRW G!avimeltProcess, consists of treating coal wi. moltencaustic (a mixture of sodium and ~siumhydroxides) at 350 to 400°C for up to fourhours. A low-ash. low-sulphur coal isproduced upon washing with water 38 diluteacid (Gala et al., 1989). Over 90% of ash andsulphu,~reduction is attained. O~ of thedifficulties of the process is the recovery of thecaustic solution to produce dry caustX:: flakes.Chriswell et al. (1991) reyorted that ~ssiumhydroxide, which is an expensive dJemical,may not be required for most coals, with theexception of high tank coals. Microwaveirradiation was found to promote the rate ofdesulphurization by facilitating the contactbetween coal and the molten (Haya.'ihi et al..1990). Microwave irradiation followed bymagnetic desulphurization is also refX)ned toenhance sulphur removal (Rowsoo and Rice.1990).
Oxidation Treatments: Coal powder is leachedwith a solution containing dissolved oxygen orair at 120- 200°C under 10-40 atm partialpressure for 1-2 h under either alkaline ormildly acidic conditions. This is the basis ofthe Ledgemont Oxygen Leaching Process(.Sareen. 1977). An iron complexing agent isused in the Promoted Oxyde-sulphurizationProcess. While the PETC Oxyde-sulphurization Process is conducted at acidicconditions. the AMES Process employs analkaline solution containing 0.2 M sodiumcarbonate. The Chlorinolysis Process (Hsu etal., 1977) utilizes chlorine as an oxidant at SO-100°C. This method is capable of removing upto 70% of the organic and 90% of the pyriticsulphur. Chlorine levels in the clean productare reduced to less than I % by hydrolysisfollowed by dechlorination. The use of ferricsalts under acidic conditions can remove up to95% of the pyritic sulphur. andHydrogen is the main reducing agent used inreduction processes such as the lOTHydrodesulphurization process which employshigh temperatures (8000C) and atmosphericpressure. Pretreatment by oxidation in air at400°C prevents caking and also helps'subsequent removal of the organic sulphur byhydrotreatment (Attar. 1978). Details ofhydropyrolysis methods of coaldesulphurization given by Sugawara et al.(1991) and Schobert (1992) are beyond thescope of this chapter.
E~"'"-',
~~
Wet Chemical Methods: These methodsinvolve the use of both gases and liquids in thepresence of various chemicals such as metalsalts. acids and bases. and can be classifiedaccording to the treatment mode.
Radiatioll-Chemical ",et/,ad.\" : The ~ulphu-rization of coal under the intluen~ oI1-raysand accelarated electrons appeaB to be a
promising method bec.1U,.~' of the- highselectivity induced by radiatiOR~mical
Desulphurization of ~ 261
reactions (Roy, 1983; Mustafaev. 1992). Thehigh electron density around the sul.phuratomas opposed to the other elements in coal (C, 0,H) makes the adsorption of radiation energythrough sulphur more effective. The chemicalbonds of sulphur, and in particular, aliphaticand bridge bonds decompose more easily; 60%desulphurization has been achievedc; on alignite sample containing 4% Sunder 1-radiation (0= 30 kJ/kg) at 400°C (Mustafaev.1992).
20.3 RECOVERY OF SULPHUR OXIDESIN THE BOILER DURINGCOMBUSTION
20.3.1 (.'luidized-Bed Combustion (FBC)
The FBC of coal represents an in situ sulphurremoval technique. It consists of addinglimestone or other metal oxides to the burningbed of coal at a stoichiometric ratio oflimestone (Shilling, 1983; Pawliger and Mudd,1985). The FBC boilers have been developedinto a commercially viable technique for coalcombustion, especially for middle and smallscale plants. Experience hitheno shows that a80% desulphurization at a ratio of Ca/S = Ican be achieved with this technology(Sadakata, 1991). The circulating fluidized-bed (CFB) can reach higher sulphur captureefficiency than FBC at the same Ca/S ratio.
Research has been conducted in ArgonneNational laboratory on Illinois No.6 coal usinga combination of lithium aluminum hydride(LAH), single electron transfer (SET), andLochmann's base (BASE) reactions (Stock,1992). The results of these investigations arepresented in Figure 20.6. While the SETreagents should be particularly effective forthe removal of heterocyclic sulphurcompounds, BASE is expected to react withsulphidEc sulphur compounds.
20.3.2 Limestone Injection Multi Burners(LIMB)
This dry additive method is another p()(entialtechnique that has attracted attention followingthe development of new low NOx burners. Ithas been studied mostly in the USA and testedon full scale plants in several countries. Usingstoichiometric ratios of 2-5 of limestone. theS02 emission can be controlled in the range of50 to 60% with proper cleaning or blending(Werhane et ai.. 1991). The sorbent injectionis expected to reduce S°3-c-oncentration and inturn solve the problem of cold end corrosionand to improve the overall efficiency. Thismethod seems to be applicable only to highrank coals. as low rank coals may have the riskof losing the flame. Since a plant adoptingLIMB is equipped with electrostaticprecipitators. limestone injection also causesserious waste disposal problems. Anotherlimestone injection technology (LiFAC)exploiting limestone injection into the furnacefollowed by calcium oxide activation seems tob~ promising as wel').
Chemical beneficiation processes such as theMLC generally produce better quality coal interms of ash and sulphur than any physicalbeneficiation process. However, theprocessing costs for coal in the MLC Process(S2-3/GJ) are significantly higher than those ofthe physical cleaning processes (SO.3-0.6/GJ)(Hucko et al., 1988). In general, the cost ofrecovering chemical oxidizing agents, e.g.ferric salts, chlorine and ozone is rather high.
Figure 20.6 De.\'lilphuri:ation of l//inoi.\' No.6 coal(hrough a combination (if LAH. SET. and BASErear.rjpn.\', --~~~~~~
J ,- --=,:i":'),.,roo.
,~-. ~~_.~~~~~~~~..-- c~_..~~-::-:
262 COAL
20.4 POST COMBUSTION SCRUBBERSAND PRECIPITATORS
concentrated aqueous solution cff sodiumsulphite to produce sulphite/bisulphia liquorwhich is then steam treated to driv.e «f 5°2-The sodium compounds are retunBd to theabsorber. whereas the 502-rich off ~ isfurther processed to obtain sulphur.iI: acid orelemental sulphur-
Flue Gas Desulphurization (FGD) is tk onlycommercially available desulphurizatioo tech-nique that has gained wide acceptaln by thepower industry (Karsten, 1983). Wet JXO(;essesusing calcium based sorbents ale ~ mostwidely adopted FGD systems. However, only15-20% of the operating boilers in tIx: utilityindustry are equipped with SCI-~rs todesulphurize the flue gas (Hucko et al.. 1988).A classification of FGD Processes is given inFigure 20.7 (Klingspor and Cope. 1987).Nongenerable FGD Pl:QCesses thai poducesalable byproducts and include the d80wawaysystems producing residues for ~aI areincreasingly favored. Regenerabk FGDsystems with a regeneration step to releaseconcentrated 8°2 are also in use, ahhoughthere are few installed in coal-fired plants.
The Magnesium Oxide Process: T£ processutilizes MgO as an absorbent for S~Rmovalin the wet scrubber. The magnesiU8 mlphateproduced is calcined to regenerate ~ MgO.which is then sent back to the utility~
~4
The Ammonium Sulphate Process: ~oniais injected into the flue gas in - processwhere it reacts with 5°2 to Conn .amnoniumsulphite. which is captured in a 1M>-stagescrubber. oxidized to sulphate and ~ in aspray drier. The contamination of aImlOniumsulphate with metal ions precludes .use as afertilizer (Karsten, 1983).
.-iNOXSO Process: The NOXSO pnIraS is adry, regenerable flue gas treatment ~ thatsimultaneosly removes 90% of ~ SO2 and70-90% of the NOx from flue gas aeneratedfrom the combustion of coal (Bali et ai.,1993). The process has been tested 00 smallscale (0.017 MW) on a high s~ coal(2.5%)._The NOXSO sorbent consisa of 1.23mm djameter alumina beads impreZ.-led with5.2% Na. which removes the Saz ..t NOxfrom the flue gas as it p~ses throup &be fluid-bed absorber. -
Figure 20.7 Classification of FGD procr.ues(Klingspor and Cope. /987).
20.4.1 Regenerative FGD Systems 20.4.2 Throw-Away FGD System
Regenerative systems are more complex. moreexpensive and have more operating s-oblemsthan the throw-away systems. These systemsare therefore preferred in locations wherepermits are difficult to obtain like heavilypopulated industrial areas or w~ marketexists to utilize the end product. The ~ingregenerative FGD Systems have beendeveloped.
Wet Scrubbers: Wet scrubbers we lime orlimestone are the most widely used sysrems inFGD installations up to the larg~ cool-firedboilers. Lime or limestone grow.t to -325mesh with a solid content of 2-1 0tJ. is used asthe absorbent. Processes produci. r,ypsumare increasingly being favored. Sulphurremoval efficiencies of 90% and over aresuccessfully achieved (Sadakata. J9JI). Thereaction of S02 with the lime producescalcium suJQhite and sulphate wltich areprecipitated and separated from -- mother
~~,~,'~...:""',, ..
...
The Wellman-Lord Process: The OOiler fluegas is allowed in this process to re4M:t with a
for large and relatively new power plants. theyare a less realistic choice for smaller and olderpower plants. In fact, even the larger plants arecautious about installing scrubbers because ofthe high. capital cost and operating andmaintenance costs. Therefore, the option ofcleaning coal prior to combustion is gainingmomentum among many utilities (Coal andSynfuel Technology, 1991; Coal, 1992).
Conventional dust collectors such aselectrostatic precipitators or bag houses, asapplied in the utility industry, can beconveniently used without much modificationin their designs (Karsten, 1983).
20.5 CONCLUDING REMARKS
The various methods of precombustiontechniques discussed in the foregoing sectionsindicate that separation of pyritic sulphur fromcoal is possible through a combination ofconventional and advanced coal cleaningtechnologies. However, the removal of organicsulphur by chemical or. biological processespresents a challenge, particularly in terms ofcost. New and more efficient technologies arerequired to implement these methods on anindustrial scale.
Studies carried out by the US Depart~nt ofEnergy reveal that for a moderate-sulphurcoal, advanced coal preparation alone issufficient to bring coal into the environmentalcompliance of 0.52 kg SO2/GJ at a verycompetitive cost, but for a high sulphur coal,duct injection combined with advanced coalpreparation provides an economicallyattractive alternative to the FGD system(Hucko et al., 1988). Other studies alsoi.1dicate that physically cleaned coalsubstantially reduces the cost of the FGDSystems; this results from only 21 % of the fluegas being processed by the FGD Systf~m asopposed to 85% when uncleaned coal is used(Holt and Deurbrouck, 1977).
Figure 20.9 presents a summary of the costeffectiveness in the USA of various coalcleaning options for SO2 reduction from coal
,'~
Laurila (1986) states that advanced coalcleaning technologies can remove sulphur at40 to 50% less cost than flue gasdesulphurization. However. an optimization isrequired to assess the level to which sulphurshould be removed physically or chemically atthe boiler. Most utilities will be required toinstall scrubbers or switch to low-sulphurcoals to meet the more stringent standardsimplemented in many countries around theworld. While scrubbers may be a viable option
100
-.c~oX
.- III
§-III0U
"0
QI
.~
"Q;>QI-J
syngas.-f
m existing technology0 developing technologies
. reflects only that portion of total~cess cost directed toenvironmental control (15-25 ~t.)
oovanced physicaland chemical coal
cleaning\
flue gas ~wet scr~..~bing.l
--- .»-II
90
eo
70
-60
.50
40
30
20
10
0
,/
physical coalcleaning"
0 10 20 30 40 50 60502 emission reduction CO'o)
70 80 90 100
Figure 20.9 Cost effectn'eness in the USA of clean CVlu(Jptions ,'ersus:;.tfstill,1,' leclinot;;gie$~r SOlreUllctioll (Yeager. J 990,.
45
40
35
30
25
20
15
10
5
"00u
--'fI+-VI0U
UQ/.~"Q;>
Q/
-J
Desulphurization of Coal2M
fired plants (Yeager, 1990). This data. indicatesthat the combination of conventiooal ,ptIysicalcoal cleaning and dry (in-furnace) sorbentinjection competes effectively with the 5°2emmision reduction achieved by theapplication of advanced physical and chemicalcoal cleaning techniques (Thambimuthu.1993). It should be noted that the data forAFBC (Atmospheric Fluidized BedCombustor) and PFBC (PressuriZed FluidizedBed Combustor) systems seem to be mosteconomic and efficient, but Couch (1991)suggests that these cost estimates fail toconsider the disposal cost of large amounts ofsolid residues generated.
Bolli. R.E.. Woods. M.C..Madden. D.L"Corfman. D.W.. (1993). "Noxso:A No-W.e'Emission Control Technology", Proce., of the18th International Conference on Cotw' Iftit.ationand Fuel Systems. Florida. p.403-4/4.
80S, P., Huber, T.F., Kos, C.H., Ras, c. Klenen. J.(1986), "A Ducth Feasibilty Study on l6t:DbialCoal Desulphurization", In Fundamen!J.JiadApplied Bioh)'drometallur
Chatterjee. K.. Wolny. R.. Stock. L.M., (1990),"Coal Desulphurization by Single ElectronTransfer Reactions". Energy and Fuels, Vol. 4,p.402-4£M.
Fan, J., Y ung-Song, Y., Zhang-Shen, L.. (1982),"Study on Application of Centrifugal Table forFine Coal Concentration", Proceedings of NinthInternational Coal Preparation Congre.u. NewDelhi.
Chriswell, C.D., Markuszewski, R., Norton, G.A.,(1991), "Use of NaOH Alone vs. Mixtures for theRemoval of Sulphur and Ash from Coal by theMolten Caustic Leaching Process", P.R. Dugan.D.R. Quigley. Y.A. Attia. Eds.. Elsevier Processingand Utilization of High Sulphur Coals IV.p.385-397.
Gala. H.B., Srivastava, R.D., Ree, K.H.. Bucko,R.E., (1989), .. An Overview of the Chemistry of
the Molten Caustic Leaching Process", u-,/Preparation, Vol. 7, p.I-2B.
~Coal, (1992), Maclean Hunter Publishing,Chicago, Illinois, Vol.97, No.8, Aug.
Gallagher, E., Ellis, R.. Pitt. G.. Partridge.A.C..Randell. J.K.. (1986). "Operation of a 300~Spiral Concentrator Circuit at The Gemlaa CreekPreparation Plant", Proceedings of TenthInternational Coal Preparation Congr~ss.Edmonton. 1986.
Coal & Synfuel Technology, (1991), PashaPublication, Arlington, Virginia. Vol.12, No.44.Nov.
Gokcay, C.F., Yurteri, H.N., (1983), "MaobialDesulphurization of Lignites by ThennOlblicBacterium", Fuel. Vol.62, p.1123-1124.Couch, G.R., (1991), "Advanced Coal Cleaning",
Report No.lEACR/44, lEA Coal Research, London.UK.
Detz, C.M., Barvinchak, G., (1979), "MicrobialDesulphurization of Coal", Mining CongressJournal, Vol.65, p.75-86.
Goss, W.L., (1993), "Flue Gas De3ulphmization ofHigh Sulphur Coals", Proceedings of the 18thInternational Conference on Coal Utililtllion andFuel Systems. Florida, p.403-414.
Gullu, G., Durusoy, T., Ozbas, T., Tany*, A.,Yurum, Y., (1992), "Biodesulphurization of Coal",Nato AS! Series. 1': Yu~ Ed, Vol.370. p.J85-205.
Dogan. M.Z.. (1990). "Coal Desulphurization byMicrobial Beneficiation". G.I. Karavaiko, G.Rossi, ZA. A vakyan, Eds., Proceedings ofInternational Seminar on Biohydrometallurgy,Moscow.
Hall, S.T., Finch, I.A., (1984), "EnhancedMagnetic Desulphurization of Coal", Minerals andMetallurgical Processing, Vol.J, Nov.
Dogan, M.Z., Ozbayoglu, G., (1985), "BacterialLeaching vs. Bacterial Conditioning and Flotationin Desulphurization of Coal", XV InternationalMineral Processing Congress. Cannes. p.304-314.
Hayashi, J., Oku, K.,Kusabake, K., Merooka, B.,(1990), "Role of Microwave Irradiation in CoalDesulphurization with Moiteri Caustic", Fuel.Vol. 69, p.739-742.
Holt, E.C., Deurbrock. A. W.. (1977), "CoalCleaning with Scrubbing for Sulphur Control".Report No.Epa-60019-77-0/7.
Dogan, M.Z., Celik, M.S., (1992), "LatestDevelopments in Coal Desulphurization byAotation and Microbial Beneficiation",Proceedings of the Third Mining, Petroleum andMetallurgy Conference. Cairo. Vol.J. p.385-393.
Horsfall, D.W., (1988), "Cost Effective Routes inFine Coal Preparation", In Industrial Practice ofFine Coal Cleaning. R.R. Klimpel. P. T. lJIckie.Eds.. SME Publication. p.365-374.
Dugan, R.P., Apel, W.A., (1978), "MetallurgicalApplications of Bacterial Leaching and RelatedMicrobiological Phenomena", LE. Murr, A.E.Torma, l.A. Brierly, Eds.. New York. AcademicPress. p.223-250.
"i,~~I'
.~~.~~
Howard, P.H., Datta, R.S., (1977), "Coal
Desulphurization", Chemical and Ph.vsicalMethods. T.D. Wheelock. Ed.. ACS S.v"'POsiumSeries No.64. Washington DC. p.58-69.
- - -.. -- -~-~--
EI-Zeky. M.. Attia. Y.A.. (1987). "Coal SlurriesDesulphurization by Flotation Using ThiophilicBacteria for Pyrite Depression", Coal Preparation.Vol. 5.9'
~
Desulphurization of Coal 267
Hsu, G.C., Kalvinskas. J.J., Ganguli, P.S~,Gavala$,G.R.. (1977), "Coal Desulphurization", Chemicaland Physical Methods. T.D. Wheelock. Ed.. ACSS)'mposium Series No.64. p.206-2/7.
Matoney,J.P., Harrison, K.E.. Kern, K.. (1988),"Coal Preparation: Past. Present and Future.,Industrial Practice of Fine Coal Cleaning. R.R.Klilnpel, P. T. LuCkie. Eds.. SME Pttblication, p.3-9.it
Hucko. R.E.. Gala. H.B., Jacobsen, P.S., (1988),"Status of DOE-Sponsored Advanced CoalCleaning Projects", Industrial Practice of Fine"Coal Cleanin,~. R.R. Klimpel, P. T. Luckie. Eds..SME Pllblication. p.159-2ID.
Mehrotra, V.P., Sastry, K.V.S., Morey, B.W.,(1983), "Review of Oil Agglomeration Techniquesfor Processing Fine Coals", International Journalof Mineral Processing, Vol.II, p. I 75-201.
Meyers, R.A., (1977), Coal Desulphurizatioo.Marcel Dekker, Inc., New York.1m, C.J., Aplan, F.F., (1981), First Australian Coal
Preparation Conference, A.R. Swanson, Ed., Newlyand Beath Printers, p.J83-204.
-4Miller, K.J., (1973), "Flotation of Pyrite fromCoals: Pilot Plant Study", US Bureau of MinesResearch and Investigatiqns, No. 7822.Isbister, J.D., Koblynski, E.A., Anspach, G.L.,
Kitch,eos, J.F., (1986), "Biological Removal ofOrganic Sulphur from Coal", SME AnnualMeeting, p.86-156.
Miller, K.J., (1988). "Novel FlotationTechnology", Industrial Practice of Fine CoolCleaning. R.R. Klimpel. P. T. Luckie, Eds.. SMEPublication. p.347-363.Kargi. F.. Robinson, J.M., (1982), "Removal of
Sulphur Compounds from Coal by the ThennophilicOrganism.Sulpholobus Acidocaldaritus", AppliedEnvironmental Microbiology, Vol.44, p.878-883.
Miller, KJ., Deurbrouck, A.W... (1978), "NewPhysical M~thods for Cleaning Coal", Y.A Lieu.M. Dekker. Eds.. New York. p.255-29/.'04
Karsten. F.. () 983). "Desulphurization of LowRank Coals", The Ankara Energy Meeting on NewCoal Technologies and Policies, Oct.
Miller, J.D., Ye, Y., Pacquet, M.W., Baker.M.W.,Gopalakrishnan, S., (1988), "Design and OperatingVariables in Flotation Separation with the Ash",Proceedings of Sixteenth International MineralProcessing Congress, K.S.E. Forssberg, Ed.,Stockholm, Elsevier, p.499-5/0.
~
Kempton. A.G.. Mone, B.A.. McCready, R.O.,Capes. C.E.. (1980), "Removal of Pyrite from Coalby Conditioning with Thiobacillus FerrooxidantsFollowed by Oil Agglomeration",Hydrometallurgy. Vol. 5.
1 Klingspor. J.S.. Cope, D.R., (1987), FGDHandbook. lEA Coal Research.
Koch, G.H., Rosenberg, H.S., (1987), "MaterialIssues in Flue Gas Desulphurization Systems",Proceedings of Fourth Annual Pittsburg CoalColljerence. p.594-60J.
Mills, 0.. ~heng, Z., (1993), "Electrostatic CoalBeneficiauon", Proceedings of the 18thInternational Conference on Coal Utilization andFuel Systems. Florida. p.577-589.
Mustafaev, I., (1992), "Radiation Them1alMethod.. of Coal Processing", Fourth InternationalMineral Pocessing Sympo...ium. Vol.2. Antalya.
Tiirkiye. p.866-875.
Kolb. H.. Steiner. H.J.. (1986). "Dynamic HeavyMedium Separation of Lignite Containing WaterDegradable Waste Material". Proceedings of TellthInternatiOllal ClHU Preparcltion Congre.\"s.EUnlOlltlJfl.
Olson. G.J.. Brinckman. F.E., (1986),"Bioprocessing of Coal", Fuel, Vol.65. p./638-/646.
Ozbayoglu. G., (1986), "Desulphurization ofLignites by High Gradient Magnetic Separation".The First lntemati(ma/ Miner(// Proces.~inKSympi)siuln. Vo/.2. i:Jnir. Tiirki.\'e. p.635-645.Laurila. M.. (1986). "Advanced Physical Coal
Cle3.ning - An update". Coal Magazine~ Feb.
Pawliger, R.I., Mudd. M.J., (1985). "PressurizedLua. A.C., Boucher. R.F.. (1990), "Sulphur and Auid-Bed C.<:!!!!b_~gi<ln !~roHjl;J! SulphurAsh Reduction in Coal by HGMS", Coal Utilization~~tiCl17liljl.lHH}n (if /fighPreparation. Vol.8. p.6l-71. SlllphlirCOitl.\". Y.A. Attici. Ed~El\'ey[ey._SI3-52~
II
Perry, R. W.. Aplan, F.F., (1985), "Polysaccharidesand Xanthated Polysaccharides as PyriteDepressants During Coal Flotation", Processingand Utilization of Hi.~h Sulphur Coal.\'. Y.A Attia.Ed.. Elsevier. p.2/5-238.
Sinha. R.K.. Walker. P.L.. (1972). "Removal ofSulphur from Coal by Air Oxidation at 350-450°C".Fuel. Vol.51. No.4.
Stock, L.M.. (1992), "Toward OrganicDesulphurization", Energia, Univer.rity ofKentucky Research. Vol.J, No.1. p./-J.Read, R.B., Meyers, C. Y., Camp, L.R., Summers,
M.S., (1989), "Improving the Aoatability andCleanability of Ultrafine CoaJ by the Use ofAnionic Surfactants", Coal Preparation, Vol. 7.p.85-//4.
Stock. L.M., Wolny, R., BaI, B., (1989), "SulphurDistribution in American Coals", Energy andFuels, Vol.J, p.65J-66J.
'1t
Stonesb'eet. P., Franzidis. J.P.. (1988), "ReverseFlotation of Coal", Minerals Engineering, Vol.J,p.343-349.
Rowson. N.A.. Rice. N.M.. (1990)."Desulphurization of Coal Using Low PowerMicrowave Energy". Minerals Engineering, Vol.3,p.363-368.
Roy, B., (1983). US Patent No.4406-462.Sugawara. T., Sugawara. K., Nishiyama. Y.,Sholes, M., (1991), "Dynamic Behavio'Jr ofSulphur Forms in Rapid Hydropyrolysis", Fuel.Vol. 7O, p.I09I-I097.
Sadakata. M., (1991), .. Adaptable Treatment
Processes and Problems on Acid Rain Issues",Handbook/or Global Environmental Engineering,Y. Kaya. Ed., Ohmsha Company LJd.. Tokyo.Japan. p.678-685.
Thambimuthu. K. V., (1993), "Strategy for CoaI-Liquid Mixture Commercialization", Proceedings ofthe /EC Coal Mixture Workshop, Florida.p./-43.
Sareen, S.S., (1977), "Coal Desulphurization",Chemical and Physical Methods. 7:D. Wheelock,Ed. ACSSympos;um. Series No.64. p.J73-/8J.
Tonna. A.E., Gundiler, I. H., (1986), Proceedingsof the First International Mineral ProcessingSymposium. izmir. Tiirkiye. Vol.2. p.602-612.
Schlepp, D.O., Schmidt, M.P., (1988), "When toUse Water-Only-Cyclones", Industrial Practice ofFine Coal Cleaning, R.R. Klimpel, P.T. Luckie,Eds.. SM E Publication. p.81-86.
Werhane, J.A., Depriest. W.. Slot. D.G.. (1991),"Combining S02 and NOx Control Technologies asa Strategy for Environmental Compliance".Conference,im Clean Power from Coal: World- WideMarket Oppununities, Brussels, Belgium. Oct.Schobert, H.H., (1992), "Biodesulphurization of
Coal", Nato AS/ Series, VoL370, Y. Yurum, Ed.,p./73-/83.
Schuctz. G.H.. Serrini. G.. (1988), "Fine CoalDesulphurization by Leaching With BromineContaining Hydrobromic Acid", Fuel, Vol. 67,p.595-/598.
Wheelock. T .D.. Markuszewski. R.. (1981)."Physical and Chemical Coal eieaning".Chemistry and Physics of Coal Utilizatioll. B.R..Cooper. L Petrakis. Eds.. American Institute ofPhysics. New York. p.357-387.
Wills, B.A., (1985), "Coal Preparation. MiningAnnual Review".Shah. C.L.. Shaw. S.R.. Strike. E.. Deeley. W.T..
(1982). "A 250 t/h Centrifugal Dense-MediumSeparator for Minus 100 mm Raw Coal".Proceedings of 16th InterntitionaJ CC)(IJPreparation Congress. Ed",ontan.
Yeager, K.E., (1990), "Coal in the 21st CenturyEnergy W(Jrld. No./79. h,ne.
Shilling. H.D.. (1983).Technology - State of tChemical Engineeringp./85.
Yoon, R.H., Lagno. M.L., Luttrell. G.H.,Mielczar!iki, J.A., (1991), "On the Hydrophobicityof Coal Pyrite", Processing :md Utilization ofHigh-Sulphur Coal!i IV", P.R. Dugan. D.R.Quigle)'. Y.A. Allia. Ed.5.. Elsevier SciencePublisher.\'. Amtterdam. -~- ~- ~ --
j
j
~
~
-
"Fluidized-Bed Firinghe Art and Prospects",Technology. Vol. 55,
