ASTM_D_6781_-_02_2014.pdf

Designation:D678102(Reapproved 2014)Standard Guide forCarbon Reactivation1This standard is issued under the fixed designation D6781;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This set of guidelines is offered to users of activatedcarbon to provide a better understanding of the reactivationprocess and some of the problems associated with sendingcarbon off-site or to a third party for thermal reactivation.It isnot intended to serve as an operating procedure for thosecompanies or persons that actually operate reactivation facili-ties.This is true because each reactivation facility is unique,using different types of furnaces,using various operating andperformance requirements,and running spent activated car-bons either in aggregate pools(combining different suppliers ofcarbon)or in custom segregated lots.Additionally,proprietaryinformation for each facility relative to the particular equip-ment used cannot be addressed in a general set of guidelines.1.2 This standard does not purport to address any environ-mental regulatory concerns associated with its use.It is theresponsibility of the user of this standard to establish appro-priate practices for reactivation prior to use.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory requirements prior to use.2.Referenced Documents2.1 ASTM Standards:2D2652 Terminology Relating to Activated Carbon2.2 Other Standard:AWWA B605-99 Standard for Reactivation of GranularActivated Carbon3.Terminology3.1 Definitions:3.1.1 reactivated carbonspent activated carbon that hasgone through a thermal reactivation process.3.1.2 spent activated carbonactivated carbon that hasseen service in some application,and that has some adsorbateon the carbon.3.1.3 virgin carbonactivated carbon produced from a rawmaterial carbon source that has never seen service.4.Procedure4.1 Thermal Reactivation Process:4.1.1 In order to appreciate the parameters or properties ofthe spent activated carbon that influence the success of thereactivation process,one must have a basic understanding ofthe reactivation process and the equipment used therein.Basically,the equipment and process used for reactivation issimilar,if not identical,to those same items used for activationof coal,coconut,wood,or other chars,into activated carbon,post devolatilization and carbon fixation(which are necessarysteps in virgin carbon manufacture).4.1.2 The equipment used for these types of processesusually consists of rotary kilns,vertical tube furnaces,fluidizedbeds,or a multiple hearth furnace.All of these can be fireddirectly or indirectly.Auxiliary equipment to the furnace orkiln consists of feed screws,dewatering screws,direct feedbins,dust control equipment,product coolers,screeningequipment,off-gas pollution abatement equipment,and tank-age.4.1.3 The spent carbon can come from either liquid or gasphase service.Thus,the spent carbon will contain more or lesswater(or other liquids)depending on its serviceless for gasphase service compared to liquid phase service.Additionally,the carbon could be fed to the furnace as a water slurry ifreceived in a bulk load,or if the spent carbon was slurried outof adsorbers.Gross dewatering of such a slurry is normallydone by gravity separation of the water from the carbon in aninclined dewatering screw.4.1.4 Once the spent carbon is introduced into the reactiva-tion furnace,the carbon undergoes a three-step process.As thespent carbon progresses through the furnace and is heated up,the carbon first loses moisture and light volatiles;then thecarbonlosesheaviervolatilesbyacombinationofvaporization,steam stripping,and thermal cracking of heaviesinto a pseudo-char which deposits in the pores of the carbon;1This guide is under the jurisdiction of ASTM Committee D28 on ActivatedCarbon and is the direct responsibility of Subcommittee D28.02 on Liquid PhaseEvaluation.Current edition approved July 1,2014.Published September 2014.Originallyapproved in 2002.Last previous edition approved in 2007 as D6781 02(2007).DOI:10.1520/D6781-02R14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 and then,the char is removed from the pores by gasificationwith steam.This three-step process normally relies on thecarbon being heated from ambient temperature to a tempera-ture app