EPA/600/2-86/015
                                            January 1986
      DESIGN AND CONSTRUCTION OF A MOBILE
      ACTIVATED CARBON REGENERATOR SYSTEM
                  R. H. Hiltz
            MSA Research Corporation
         Evans City, Pennsylvania 16033
            Contract No. 68-03-2110
                Project Officer

                John E. Brugger
Hazardous Waste Engineering Research Laboratory
            Releases Control Branch
            Edison, New Jersey 08837 ^
HAZARDOUS WASTE ENGINEERING RESEARCH LABORATORY
       OFFICE OF RESEARCH AND DEVELOPMENT
      U.S. ENVIRONMENTAL PROTECTION AGENCY
             CINCINNATI, OHIO 45258

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                                             TECHNICAL REPORT QATA
                                      (Please read Instructions on the reverse before completing)
          . REPORT NO.
             EPA/600/2-86/015
                                                                       3. RECIPIENT'S ACCESSION NO.
         4. TITLE AND SUBTITLE
           DESIGN AND CONSTRUCTION OF A MOBILE ACTIVATED
           CARBON REGENERATOR SYSTEM
                                                                       5. REPORT DATE
                                                                          January  1986
                                                                       6. PERFORMING ORGANIZATION CODE

                                                                         A-918
         7. AUTHORtSI

           R.H.  Hiltz
                                                                       S. PERFORMING ORGANIZATION REPORT NO.

                                                                         MSAR 81-107
         9. PERFORMING ORGANIZATION NAME AND AOORESS

          MSA Research Corporation
          Division of Mine  Safety Appliances  Co.
          Evans City, Pennsylvania  16033
                                                                       10. PROGRAM ELEMENT NO.
                                                                       11. CONTRACT/GRANT NO.
                                                                         68-03-2110
          12. SPONSORING AGENCY NAME AND ADDRESS
           Hazardous Waste  Engineering Research  Laboratory
           Office of Research and Development
           U.S. Environmental Protection Agency
           Cincinnati, Ohio  45268
                                                                       13. TYPE OF REPORT AND PERIOD COVERED
                                                                         Final-8/6/74-2/8/79	
                                                                       14. SPONSORING AGENCY CODE

                                                                            EPA/600/12
          IS. SUPPLEMENTARY NOTES
           Project Officer:   John E. Brugger (201)321-6634
vK
          16. ABSTRACT
                 ''Activated carbon adsorption  has  become  a standard procedure for the cleanup  of
             contaminated water streams.  To facilitate  such cleanup at hazardous waste and  spill
             sites, mobile carbon, adsorption units have  been constructed and *re now in use.   Their
             primary drawback is the logistics  associated with the disposal of spent (contaminated)
             carbon and its replenishment with  fresh,  active carbon.

                  This program was undertaken  to assess  the feasibility of designing and building
             a mobile carbon regeneration unit  - including an incinerator/scrubber to destroy  the
             offgases - for field use in conjunction with mobile carbon adsorption systems.  A
             system was designed and built based on technology developed in the earlier fabri-
             cation of a laboratory-sized regenerator  and on an in-depth evaluation of factors
             affecting system design and size.  Housed in a standard van-type  of trailer, the
             system met all weight and size limitations  for over-the-road transportation.  The
             system includes a direct fired, rotating  barrel kiln to thermally regenerate the  car-
             bon, an incinerator and scrubber  to destroy the desorbed materials and treat the  off-
             gases, 2nd a separator to reclaim  the reactivated carbon granules.

                  Test runs using spent carbon  from an on-site treatment of a 'spill were quite
             successful.  The carbon was returned  to essentially 100% activity with an 88% volume
             recovery.  The unit has been delivered to the US EPA for their use...
         17.
                                          KEY WORDS AND DOCUMENT ANALYSIS
                            DESCRIPTORS
                                                         b.lOENTIFIERS/OPEN ENDED TERMS  C.  COSATI Field/Group
          18. DISTRIBUTION STATEMENT
           RELEASE  TO PUBLIC
                                                         19. SECURITY CLASS (ThisReport)

                                                            UNCLASSIFIED
                                                                                      21. NO. OF PAGES
                                                                                         54
                                                         20. SECURITY CLASS (Thisparti
                                                            UNCLASSIFIED
                                                                                     22.
IpT.
          EPA P»na 2220-1 (R«». 4-77)    PRIVIOUS COITION i* OOSOUETE
                        t^5^if^v^y^'ik.ig^«i,^^-f..&^^^

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                                   DISCLAIMER
     The information in this document has been  funded  wholly or in. part by the
United States  Environmental  Protection  Agency  under  Contract  No.  68-03-2110
to MSA  Research Corporation.   It  has been  subject to  the Agency's  peer and
administrative review,  and  it  has  been  approved  for publication  as  an EPA
document.  Mention of  trade  names or  commercial products dees  not  constitute
an endorsement or recommendation for use.
                                       ii

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                                  FORWARD
     Today's rapidly  developing  and  changing technologies  and Industrial
products and practices frequently  carry  with them the Increased generation
of solid and hazardous wastes.   These materials,  if improperly dealt with,
can threaten both public health and the environment.  Abandoned waste sites
and accidental releases of toxic  and hazardous substances to  the environment
also have  important  environmental and  public  health  implications.   The
Hazardous Waste  Engineering Research Laboratory  assists  in  providing  an
authoritative and defensible  engineering basis  for assessing  and  solving
these problems.  Its  products  support, the policies,  programs,  and  regula-
tions of  the Environmental  Protection  Agency,  the  permitting and  other
responsiblitles of  State  and local governments and the  needs of both large
and small businesses in handling their wastes responsibly and economically.

     Activated carbon is proving to be an invaluable tool in the cleanup of
hazardous chemical  storage sites  and  in  the response to  Industrial  and
transportation disasters.   The  addition  of   a  mobile  regeneration  system
such as designed  and constructed  in  this  project  will  further facilitate
the efforts of field workers and allow onsite destruction of the pollutants
from the environment.

                                       David G. Stephan, Director
                                       Hazardous Waste Engineering
                                       Research Laboratory
                                    111

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                                                ABSTRACT
                 Activated  carbon  adsorption  has  become  a standard  procedure  for  the
             cleanup  of  contaminated  water  streams.    To  facilitate  such  cleanup  at
             hazardous  waste and  spill  sites, mobile  carbon adsorption units  have been
             constructed  and are  now in  use.  Their  primary  drawback  is  the  logistics
             associated   with   the  disposal  of  spent  (contaminated)  carbon  and  its
             replenishment  with fresh,  active carbon.

                 This  program  was undertaken  to assess the  feasibility  of  designing  and
             building  a  mobile  carbon regeneration   unit  -  including an  incinerator/
             scrubber  to  destroy the offgases - for field  use  in conjunction with mobile
             carbon  adsorption  systems.   A system was designed  and  built  based on tech-
             nology  developed   in  the  earlier fabrication of a laboratory-sized regener-
             ator  and  on an  in-depth evaluation  of  factors affecting  system design and
             size.   Housed  in a standard van-type  of  trailer, the system meets all weight
             and  size  limitations for over-the-road transportion.   The system includes a
             direct  fired,  rotating  barrel kiln  to thermally  regenerate the  carbon,  an
             incinerator  and scrubber  to  destroy  the desorbed  materials  and  treat  the
             offgases,  and  a separator  to  reclaim  the  reactivated carbon granules.

                 Test  runs using  spent  carbon  from an onsite  treatment of  a spill were
             quite  successful.   The carbon was returned to essentially 100% activity with
             an 88%  volume  recovery.  The  unit has been delivered to the US EPA for their
             use.

                  This  report was  submitted in  fulfillment  of  Contract  No.  68-03-2110 by
             MSA  Research  Corporation  under  the  sponsorship  of  the  U.S.  Environmental
             Protection Agency.  This report covers a period from August 6, 1974 to February
             8, 1979,  and work  was completed as of October 15,  1981.
jf.
*?'
*s~


I
K
                                                   IV

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                                                                    •—prTr—r--*-^*- i**i-ar.-T "
                                   CONTENTS
Foreword	ill
Abstract	    iv
Figures	    vi
Tables	    vi

   1. INTRODUCTION	     1
   2. RESULTS AND CONCLUSIONS  	     3
   3. PHASE I - SYSTEM DESIGN	     5
       TECHNOLOGY ASSESSMENT	     5
         Classification of Spill Chemical  	     5
         Review of Potential Regeneration Systems  	    10
         Direct and Indirect Heating	    11
         System Functions 	    12
            Carbon Feed	    12
            Regeneration	    13
            Indirect Fired Rotary Kiln	    18
            Direct Fired Rotary Kiln	    19
            Incinerator	    19
            Scrubber	    20
       PRELIMINARY SYSTEM DESIGN	    20
       BENCH SCALE STUDIES	    25
         Bench Scale System ......  	  	    27
         Chemical Classification and Selection	    27
         Regeneration/Incineration Tests	    28
         Materials of Construction	    30
   4. PHASE II - COMPONENT SPECIFICATION DEVELOPMENT	    31
         KILN	    31
         INCINERATOR/AFTERBURNER	    34
         SCRUBBER	    35
         REGENERATOR POWER AND CONTROLS  	    37
         TRAILER DESIGN 	    38
         GENERAL REQUIREMENTS  	  	    39
   5. PHASE III - PROCUREMENT, ASSEMBLY AND TEST	    40
         PROCUREMENT	    40
         ASSEMBLY	    41
         ASSEMBLY REVIEW	    41
      .   SYSTEM CHECKOUT	    41

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                                   FIGURES
Number

   1
   2
.   3
   4
   5
   6
   7
   8
   9
   10
   11
Flow Diagram of Proposed Carbon Regeneration System   	    6
Mobile Regeneration Unit 	   21
Trailer Design	26
Enclosed Trailer   	   44
Trailer Open for System Operation   	   44
Profile of Kiln and Incinerator	45
Head End of Kiln   	45
Scrubber arid Filtration Equipment   	   46
Tanks and Pumps Beneath Trailer Bed	46
Control Panel and Product Screener    	   47
Trailer in Transit    	47
                                      TABLES

   1     Classification  of Potential Spill Chemicals Relative to
         Their  Ease of Desorption From Activated Carbons During
         Regeneration   	   8
   2     Material  and Heat Balance for Granular Carbon Regeneration
         and  Adsorbate Recovery   	  14
   3     Effect of Direct and Indirect Heating on Gas Flows for
         Thermal Des'orbtion   . . .	15
   4     Material  and Heat Balance for Granular Carbon Reactivation    .  16
   5     Effect of Direct and Indirect Heating on Gas Flows During
         Pyrolytic Regeneration	17
   6     Effluent  Gases  for Regenerators Operated Under Different
         Conditions   	18
   7     Incinerator Size Estimates  for 0.5 Sec Residence Time at
         760"C	20
   8     Process Calculation Summary  .... 	  23
   9     Estimated Weight for Mobile Carbon Regeneration Unit for
         45.4 kg/hr Direct Fired Rotary Kiln  	  24
   10     Typical Concentration of Gases Exiting From the Laboratory
         Scale  Regenerator and Scrubber   .	29
   11     Kiln Design Operating Parameters	33
   12     Scrubber Design Parameters    	  36
   13     Operating Conditions of System   	  42
   14     Iodine Numbers    	'	43
                                       VI
                                                                                           m

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                                                SECTION 1

                                               INTRODUCTION
                  One of the principal techniques now in wide use to decontaminate water is
             granular activated carbon, which has the ability to adsorb selected classes of
             chemicals preferentially from aqueous solutions or dispersions.  Activated
             carbon is characterized by a highly developed network of small pores and
             interstices which contribute to its high sur'ace-to-volume ratio and,
             consequently, to its high adsorptive capacity.

                  In spill situations where hazardous chemicals have entered the water
             ecosystem, where materials are leaching from landfills or waste storage sites,
,.,            —— i" other similar situations, activated carbon treatment becomes a standard
 !            practice.  To facilitate the cleanup at such sites, portable carbon adsorption
 |            systems have been developed in recent years.  These are trailer or skid mounted
•!            units which can be moved over the road or by air to the place where the cleanup
 !            is  to be conducted.

                  These portable systems have proven quite versatile and effective.  However,
             they have a significant drawback—the logistic and administrative barriers
             associated with the disposal of spent (contaminated) carbon and its replace-
             ment.  Large quantities of carbon are usually required for cleanup operations.
             And though the carbon can technically be regenerated commercially it must
             be  moved to a facility having the necessary processing equipment, and
             appropriate permits for carbon reactivation.  Also, fresh carbon must be
             moved to the field site to keep the cleanup operation active.  This approach
             to  regeneration can be complicated If hazardous materials are involved
             (such as PCB's or TCDD) for which there are strict regulations or prohibitions
             affecting commercial reactivation.  Commercial regeneration facility operators
             are unwilling to operate their equipment routinely at the temperatures needed
             to  destroy PCB's and TCDD because of economic reasons.  Further, the regeneration
             market for carbon contaminated with these substances is not large enough to
             justify the facility operator's incurring the public concern that would result if
             the facility were to accept such substances.  Because of these problems with
             commercial reactivation, carbon used to treat PCB's or TCDD is currently being
             disposed of in chemical landfills rather than being regenerated.  Thus, the
             toxics accumulated on the carbon are not destroyed, only stored, possibly to
             enter the environment in the future.

                  Clearly, the utility of portable activated carbon systems (particularly
             when used on toxic chemical contaminated carbon not commercially regenerable)
             could be enhanced if regeneration of the carbon could be achieved at the
             cleanup site.  Since the adsorption system has been adapted to a mobile base,
             it  was not difficult to conceive of a regeneration process that could be
             fitted onto a skid or mobile trailer bed.

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                                                                                 BVK-a^a
     Host materials that can be adsorbed by carbon can be stripped by means of
cteam or other thermal treatments to regenerate the adsorptive capacity of the
carbon. The residue from this stripping then contains the adsorbed materials
(in an aqueous carrier) at a much higher concentration but in a iduch smaller
volume than in the original contaminated water.  This residue must be disposed
of, however, which still may require transport to an acceptable facility.  To
be most effective, the regeneration system should strip the adsorbed material
and convert it to a form suitable for disposal at the spill site.

     In a prior Federally sponsored program (Juhola, A.J., "Laboratory
Investigation oC the Regeneration of Spent Activated Carbon", U.S. Public
Health Service, Contract No. 14-12-469, Final Report MSAR 70-184),
a laboratory-sized carbon regeneration unit was developed that used thermal
treatment to strip the adsorbed material from the carbon.  This unit was
coupled to a gas-fired incinerator to provide high temperature thermal
destruction of the stripped material.  The laboratory unit served as a start-
ing point for the design of a portable unit to provide onsite carbon regenera-
tion and waste material incineration.              ,

     The goal of the current program was to design, construct, and test a full
size mobile system for field regeneration of carbon. Several tasks were pur-
sued toward this goal. These included:

     (a)  an in-depth assessment of existing carbon regeneration technology;
     (b)  selection of representative pollutants for which such a system might
          find use;
     (c)  preparation and evaluation of a preliminary design;
     (d)  laboratory-scale studies of the proposed design;
     (e)  modifications of the design into final specifications for fabr.i-
          cation;
     (f)  fabrication of a mobile system; and
     (g)  shakedown testing of the unit prior to transfer to the US EPA for
          further testing and field use.

     The studies undertaken for each of these tasks are reported In the vari-
ous sections of this report.


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                                   SECTION 2
                            RESULTS AND CONCLUSIONS
     The program was  successful  in designing and fabricating & trailers-mounted
carbon regeneration  system  based  on  design  calculations  and  testing  of  a
laboratory-scale system.  The system consisted  of a rotary kiln thermal regen-
erator, an incinerator  or after  burner  to degrade the material  stripped  from
the carbon,  and a  scrubbing tower  to  remove  undesirable materials  from the
offgases.

     The unit  is  self-contained  for operation  at  a  spill or  hazardous  waste
site when deployed near a source of fresh water and provided with fuel.   As
constructed, the system is  capable of  regenerating 45.4  kg/hr of >40-mesh size
granular carbon with <20% carbon loss and restoration of >75% of the adsorptive
capacity.

     Although indirect heating  of such  a  kiln offers many  advantages,  weight
and size restrictions forced the selection of direct firing for the kiln.  Even
then, an initial  goal of a  mobile system capable  of  regenerating  91  kg/hr of
carbon could not be achieved and the size was reduced by 50%.

     System design parameters were imposed by trailer limitations  of  size and
weight and expected  over-the-road  stesses.   Lightweight  and  resilient  fabri-
cation was  emphasized  throughout,  including  light  structural  containment,
ceramic fiber thermal insulation, and flexible piping.

     The system is constructed in a specially modified semi-trailer van that is
2.44-m-i-wide, 13.7-m-long,  and  4.1-m-high when  closed for storage  or transit.
When fitted  for transport by tractor-truck  or  rail piggy-back,  the  van meets
all applicable requirements, regulations, and conventional load limits.

     Using the system and a carbon contaminated with Toxaphene and minor amounts
of other chlorinated  hydrocarbons,  regeneration gave an 88%  volume  yield  of a
completely reactivated carbon based on iodine numbers.

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                 tyJBff'^F^Pi'y^^iTO^

     A pilot run was made with an activated carbon material contaminated with
toxaphene (CjoHjoClfc) and minor quantities of other chlorinated hydrocarbons
Carbon loadings  were 13%  contaminant and  52%  water.  Regeneration  gave an
83% volume  yield of a  completely  reactivated material  based  upon iodine
numbers.  Vent gas analysis showed CO and hydrocarbons to be below detectable
limits.

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                                              SECTION 3

                                 PHASE I - PRELIMINARY SYSTEM DESIGN


                 The first phase of the program was directed to the development of a data
             bace  which  would  permit  the' design1' of"  a  field   scale~portable  carbon
             regnerati'on  system.    It  was  divided  into  three  tasks :    a  technology
             assessment  of   carbon  regeneration,  a   review  of   adsorbate/carbon
             characteristics, and a preliminary system design.

             TASK I - TECHNOLOGY ASSESSMENT

                 Work in this task was directed to the identification of those techniques
             which  could  be  considered  for  carbon regeneration  and  management  of  the
             stripped waste and assessment of their suitability to a mobile system.

                 Based  on the  desired characteristics of a mobile  carbon regeneration
             system and the  expected  behavior of  the major categories of spill-chemicals
             during  thermal   regeneration,  the  major  components  of  a basic  system  are
             given  in the  schematic  flow diagram  of Figure 1.  This system is based upon
             the  laboratory   unit  previously built by  MSA  and  includes  the following
             representative operations,

                        1.  Carbon feed
                        2.  Regeneration/activation
                        3.  Carbon recovery and sizing
                        4.  Condensation
                        5.  Decantation/distillation or other method of
                            concentration
                        6.  Thermal  incineration
                        7.  Scrubbing  and scrubber  liquid  treatment.

                 Of  these major  system operations,  the   regenerator/activator,  is most
 j            critical.    Other  component requirements  are dependent  on the  design  and
 .1            characteristics  of  the  regeneration/activation  operation.     Illustrative
             calculations  were  made to  define  this dependency  and  to allow preliminary
             assessment of candidate systems.

:"'      '      Classification of  Spill Chemical
vj
                  Surveys  conducted  on  spillage  of polluting  materials  show  a great
             variety  of chemical  substances  that  may  become objects  of water  cleanup
             operations.   The  objective  of this part of  the  study  was to evaluate  this
             great  variety   of chemicals  relative to   their  ease   or  difficulty of


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                     ^^iK:j^r{;^r^.^^^-*"*'.^^c?«^^r-";^r^^l^^*^^i^^ "~^ "* ^^"^^^"^ i^:>->.'^"7-^T~";j.^
(•/   •
                                                                  Off-gas Line f
                                                                       Noncondensable
                                                                          Gas Line
                                                                      _        1
                                                  Thermal

                                                Regenerator
     ^Granular
I Water  Slurry of
 Spent Carbon,
 Silt and  Other
 Foreign Material

     x-	' Powder
         As  Above
                                  Filter
                    Indirect Heat   t
                        Propane  I
                        Combustion
                                                   On-size
                                                   jgenerat
                                                   Carbon
                                                    Spray
                                                    Sol'n '
                                        Steam
              Condenser    f
                         Condensabjes j
                                                                 Direct  Heat
                                                                 Propane
                                                                 Combustion
     urr-size      /    \/Vater  x.uHea,y,ieir
     Material   , .nLaf  soi'n    than Water
                Lighter  001 n      rhom;A«i
Vent Gas
                                                                                than
                                                                               Water
                                                                                                  Chemical
                                             Scrubber
                                                                                        Incinerator
                                                                                           Air  or
                                                                                     Propane  Combustion
                                                                                           Gas
                            Figure  I.   Flow diagram  of  proposed  carbon  regeneration  system.

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 desorption from  Che carbon  and  to  determine  what steps  must  be  taken  to
 collect the desorbed chemical; and avoid further air or water pollution.

     Spill  chemicals were  classified  into  five  groups  according  to  their
 distinctive regenerative  patterns.   Table  1  presents a  partial  listing  of
 each group showing typical chemicals and range of properties.

     Groups 1  and 2  are  relatively  volatile  and have small  molar volumes.
 Both  properties  correlate  with  relatively  low  to  moderate  adsorptive
 affinity, hence these two groups will be desorbed quite readily.  At a 350°C
 final  regeneration  temperature,  recovery  of  over 80%  of  the  adsorptive
 capacity can be  expected.   Some  decomposition  of the heavier members of the
• groups' can be expected to occur.

     Group  2  differs from group  1  in that  each  chemical  contains chlorine,
 sulfur  or nitrogen.   For  group  1, an  incineration step to  convert  the
 desorbed- chemical  to  C02  and  H20 is sufficient to avoid air pollution.  For
 group  2  a  water  or  caustic scrubber downstream  of  the  incinerator  is
 required to remove the HCl, S02 or N02 from the exhaust gas stream.

     Groups 3 and  4 are  considerably  less volatile  than  groups 1  and  2.
 Since  they  do  not  desorb  readily, higher  regeneration  temperatures  are
 required  and considerable  decomposition  of   the  adsorbed chemical  can  be
 expected.   One  of the  decomposition  products  will  be  free carbon.   Its
 accumulation  over  a  few  adsorption-regeneration  cycles can   drastically
 decrease  the carbon  adsorptive  capacity.   To  remove  the  free  carbon,  by
 steam  or  C02  oxidation,  final  regeneration  temperatures near  930"C are
 required.   Thus,  for groups  3  and 4, a  regenerator is  required  that can
 withstand  a considerably higher  temperature than  that necessary for groups  1
 and  2.   Similar  to  groups  1 and  2,   group  4 differs  from 3 in  that the
 chemicals  contain  chlorine,  sulfur  and nitrogen, requiring water or caustic
 scrubbing  after incineration  to avoid air pollution.

     Group  5  resembles groups 3  and 4 in  its regenerative behavior except
 that  the  group  5 chemicals contain  nonvolatile  metals  and leave a metallic
 oxide  or hydroxide  residues.  Alkaline metals  form  hydroxides and phosphorus
 forms  an  acid.   These leach out  to  a large extent  during the  adsorption
 phase.   Calcium, mercury, lead, copper,  nickel  and chromium form oxides or
 hydroxides which do not  leach out.  Mercuric  chloride and lead  acetate are
 strongly  adsorbed,  but are  difficult to remove.  Mercuric  chloride sublimes
 at  270°C  in the  free state but  may not  when  adsorbed.  In  this case,
 regeneration  may  not be  beneficial.    Lead  acetate  can be  expected  to
 decompose  producing a lower  lead oxide  with  a molar volume change from 100
 to  28  cc/vol.    After  a  second  adsorption-regeneration  cycle,   further
 regeneration cycles may  be  of no benefit.  Regeneration  attempts on carbons
 containing copper  sulfate,  nickel  chloride,  chromic chloride  and  similar
 inorganic  salts  can be expected  to  be  ineffective.

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i. TABLE 1. CLASSIFICATION OF POTENTIAL SPILL CHEMICALS RELATIVE TO THEIR
<- EASE OF DESORPTION FROM ACTIVATED CARBONS DURING REGENERATION

.
'• . . .. .^Group Chemical
t- Acetaldehyde
'• Acetic acid
: . Acrolein
= „. - Allyl alcohol
• . Propanone
J ,' 1 Methyl acetate
> ' Propyl alcohol
• ; Benzene
'•' . 2-Butanone
; Toluene
<-.> Pentane

:".



;


^
L
•'

';.

i :
?••
il.
l't ".


?

'•V
fc.
V;

\^
•V
vt-
X
j£
rv
5>
'"t'
-T-.
;3
I
Hexane
Acetonitrile
Acrylonitrile
Dichl or ome thane
Carbon disulfide
Propanenitrile
Dimethyl sulfide
1,2, Dichloroethane
2 Chloroform
Allyl chloride
Pyridine
Propyl amine
Propanethiol
Carbon tetrachloride
Diethylamine



Ethylene glycol
Benzyl alcohol
Hydroquinone
Maleic acid
Ben zoic acid
Phenyl acetate
Methyl pentylacet ate
3 Octanediol
Carbitol
Butyl carbitol
Phthalic acid
Ethylhesyl acetate
Glucose
Sucrose

^' • "' ' .'- • ^^»-

Density
(g/cc)
0.78
1.05
0.86
0.85
0.79
0.97
0.78
0.88
0.80
0.87
0.63
0.66
0.78
0.80
1.33
1.26
0.77
0.85
1.26
1.49
0.94
0.98
0.72
0.84
1.59
0.71



1.18
1.04
1.32
1.59
1.32
1.09
0.87
	
1.12
0.96
1.59
0.87
1.56
1.59


Solubility
in water
(g/g at 20°C)


0.4


0.33

0.0007
0.23
0.0005
0.0004
0.0001

0.075
0.020
0.0012
0.10
insol .
0.0087
0.008
insol .

very sol.
slight
0.0008
very
Solubility
in water
(g/g at 20eC)

0.038
0.012
0.788
0.0029
slight
slight
slight
soluble

0.0070
insol.
0.49
2.04
8

Liquid
molar
Vapor
pressure
vol(cc/moleXmm Hg at 25°C) 	 	
56
57
65
68
73
76
77
88
90
106
114
130
53
54
64
66
71
73
78
80
81
81
82
90
97
103
Molecular
weight
(g/mole)
62
108
110
116
122
136
144
146
106
162
166
172
180
342


750
15
270
24
170
160
19
97
100
28
490
150
90
190
400
350
45
480
220
130
350
18
240
170
105
230
Boiling or
melting
point C°C)
198 BP
205 BP
258 BP
138 MP
249 BP
266 BP
148 BP
172 BP
245 BP
231 BP
206 ht>
199 BP
146 MP
206 MP
(continued)
• • . -. ' i

-------
              TABLE  1.   (CONTINUTED)  CLASSIFICATION OF  POTENTIAL SPILL CHEMICALS
               RELATIVE  TO THEIR EASE OF DESORPTION FROM ACTIVATED CARBONS  DURING
               REGENERATION
Solubility
Density in water
Group Chemical
Ammonium acetate
Benzonitrile
Benzamidine
Benzyl Chloride
Dichlorobenzene
Benzenesulfonic acid
Dicambia
4 2,4, D acid
Ammonium lauryl sulfate
Chlordane
Ethyl enediamine-
tetraacetic acid
Diazinon
DDT
Aldrin
Trimethyl phospate
Calcium acetate
Mercuric chloride
Soli urn stearate
Mercuric thiocyanate
Lead thiosulfate
Lead thiocyanate
5 Lead acetate
Hexadecyl sulfate,
sodium salt
Mercuric sulfate
Zinc phenyl sulfate
Potassium oleate
(g/cc)
1.17
1.01
	
1.10
1.30
	
	
	
	
1.57

	
	
	
	
1.25
	
5.44
	
7.56
5.18
3.82
3.25

	
7.56
	
™~™
Molecular Boiling or
weight melting
(g/g at 20°C) (g/mole) point CO
1.48
slight
soluble
insol .
<0.0005
soluble
slight
slight
	
insol .

slight
	
insol .
insol.
very sol.
0.37
0.069
sol
0.0007
0.0003
0.00005
0.44

soluble
0.0006
0.655
soluble
77
103
120
126
147
158
220
221
267
248

292
304
334
364
140
158
271
306
317
319
323
325

344
497
556
603
114 MP
191 BP
80 MP
179 BP
179 BP
525 MP

138 MP
	
322 BP

	
	
108 MP
104 MP
197 BP
	
302 BP
	
	
	
	
280 MP

	
	
	
95 MP
I-
ft.

-------
 Review of Potential  Regeneration Systems

     Regeneration of  activated  carbon requires  the  removal  of  the  sorbed
•material.    Three methods are  available; thermal,  solvent   extraction  and
 vacuum.   The  thermal  method is the most widely used.

     Solvent   extraction  uses  leaching  by  acids,  bases  or  solvent.    It
 requires  either  chemical  reaction and  product  solubility  in  the  aqueous
 solution  or  high  solubility  in  the  solvent.    Of  the  great  variety  of
 potential  spill-chemicals, only  a  small  portion  can be  effectively desorbed
 by this method.   In  addition,   the  leaching -agent -leaves the  carbon  in a
 spent  condition and  hence  must  in turn be removed  with  water (for acids or
 bases)  or  with  heat  or vacuum (for solvents).

     Vacuum desorption is effective for  some  hard-to-desorb chemicals if the
 carbon is relatively  dry and some heat  can  be  applied.  It  is assumed in
 vacuum desorption that the deposited  species can be removed  by  lowering the
 ambient pressure with no decomposition  in  the desorption process.  The high
 water  content in the carbon  imposes a heavy  load on the vacuum  system.  The
 process is  usually   restricted  to regeneration  of carbons  used  to  purify
 gases.

     Thermal  regeneration  offers the  greatest versatility.   It  is  able to
 cope with a wide range of  materials  from those easy to desorb  to those most
 difficult to  desorb,  including those  that   may decompose  in   place.   The
 former can often be  vaporized  along  with the water.   The  other materials
 involve pyrolysis  of the  sorbed  material,  converting  them  to  a volatile
 portion,   and  a  carbon   residue.    To  control   the   carbon,  pyrolytic
 regeneration is  performed at temperatures  as high  as  871°C.    The carbon
 residue is oxidized  to CO  and hydrogen by r^eans of steam  or carbon dioxide.
 A diluent  gas   is  often  necessary to  prevent excessive  loss   of  the  base
 carbon material when exposed  to these reactivation conditions.

     Thermal   regenerators  can be designed to cover  a  range  of desorption
 conditions with simultaneous  activation.   Equipment varies primarily in the
 way in which heat  is applied  (direct  or indirect  firing)  and  the  way in
 which the carbon  is  physically moved  through the  heated zone  (rotary tube,
 multiple  hearths or  fluidized bed) .   There  are  specially designed reactors
 that use microwave heating;  or  wet air oxidation (the Zimpro process).  The
 latter two are  developmental  and not  commercially proven.

     The rotary  tube  furnace   or  kiln  utilizes internal  vanes that lift the
 carbon part  way  up  the  wall, where it  then  falls  back  to the bottom.  This
 effects  a stirring  condition  while   the carbon  moves  through  the  tube.
 Indirect  firing  involves heating  on  the  outside.    It  has  relatively poor
 heat transfer  and a  more bulky  construction than  a direct-fired unit where
 hot gases  are  passed directly  through the  tube  and directly contact the
 carbon.   As  the carbon  passes  through the  tube,  it  is  dried  in the  first
 portion,  regeneration  is  completed in  the central  portion and  reactivation
 (if necessary)  occurs in the  latter protion.   Temperature  regimes are varied
 to meet the requirements for removal  of specific sorbed materials.
                                      10

-------
     A multiple hearth  furnace  has a vertical  stack of platforms  with wiping
arms.  The carbon on  each platform is pushed toward  an  opening where it drops
to the  next  lower  level.   The platforms  are  alternately  arranged  so  that
carbon moves from the center to the edge of one  platform  and from the edge to
the center of the next  lower platform.   Gases  pass  upward  through the furnace.
Thermal distortion  of  the   multiple  hearths  is  a  known  problem.   For  that
reason, this type  of  construction would  not   appear to  be  attractive  for a
mobile unit.

     In a  fluidized  bed,  streams  of  gas  and  carbon  flow  countercurrently.
The carbon tends  to  float  as  a layer  in  the gas.   Fluidized  bed processes
provide excellent  heat  transfer  and  a  minimum  of  seals  and  moving  parts
compared to the  rotary tube and multiple hearth  units.  A fluidized  bed is a
high energy  consumer  because  of  the  increased  pressure  drop  involved  in
maintaining a fluid bed condition.  There is also  the  possibilty of increased
attrition of the  granular material,  necessitating particulate  removal equip-
ment downstream.  Multiple   beds  may also  be   required  to provide  the appro-
priate zones and conditions for  drying, regeneration and reactivation.  Although
some development work has been  done, there has been  no commercial application
of fluidized bed techniques  to carbon regeneration/reactivation.

     Treatment of  the  offgases  will probable  be  required regardless  of  the
type of regenerator used. There are differences to  be  recognized between the
direct and indirect firing units with respect  to such  treatment.  An indirect
fired unit adds only heat   to  the interior of the  system,  and  offgases  are
evaporated moisture and desorbed pollutants only.  To help  control the process,
a sweep gas  would most probably  be required.   The  sweep  gas  could  be steam,
giving a  condensable  material  that  could  be removed  prior  to  treament  of
desorbed pollutants  or their decomposition products.   In direct  firing,  the
flue gas will  contain a  significant  amount of non-condensables  (CO,  C02.  N£,
some 02) that  will  add to the  total  gas that  must  pass through the treatment
system after condensation of steam.

     On the  basis  of  the  preliminary  review,  thermal  activation  clearly
appeared to be  the  only logical choice, with  the further  conclusion that only
rotary type units  could be built  on a  scale small enough  to  fit the size and
weight limitations of an  over-the-road trailer.

     Two basic designs  were  considered  —  a rotary  kiln  and  a  rotary hearth
furnace.  Initially  there was  interest  from   manufacturers  of  rotary hearth
furnaces to investigate design modifications which would allow trailer mounting.
WJth time, however, it became clear that if modifications were possible at all,
they would take  considerable time and  effort.   Rotary kilns  appeared better
able to meet near term requirements and  the  program was directed to  that option.

Direct and Indirect Heating

     To evaluate the  potential  of direct and  indirect  firing modes  on system
design, preliminary calculations  were made  for four modes of operation.  For


                                      11

-------
these calculations, a process throughput of 91 kg/hr (dry carbon basis) was
assumed.  These modes of operation are defined as follows:

   1.  Combination of direct-fired regenerator arid carbon loaded (saturated)
       with groups 4 and 5 chemicals.

   2.  Combination  of indirect-fired  regenerator  and  carbon  loaded  with
       groups 4 and 5 chemicals.

   3.  Combination of direct-fired regenerator and carbon  loaded with groups
       1, 2 and 3 chemicals.

   4.  Combination  of indirect-fired  regenerator  and  carbon  loaded  with
       groups 1, 2 and 3 chemicals.

   In mode  1  high  temperatures  up to 927°C are  required  to  give an active
carbon product.  Three reactions occur:  (1) vaporization of th» water; (2)
pyrolysis of the chemical, releasing a volatile product and depositing free
carbon and  (3)  steam oxidation  of  the  free  carbon  (steam  activation).

   In mode  2, temperatures  and  reactions are the same  as  in mode 1 except
that indirect  firing considerably  reduces the  volume of  gases  that  are
emitted from the regenerator. As  a result,  the downstream components of the
system are smaller with more efficient condensation recovery.

   In mode  3, lower  temperatures  are used, the  maximum being about 316°C.
In this case  only  vaporization  of the water and desorption of the chemical
are involved.  The  large  volume of flue gas  from direct  firing limits the
efficiency of condensation recovery.

   In mode  4, the  temperature and reactions are the same  as mode 3 except
that with indirect firing, the volume of noncondensable gases in the regen-
erator effluent is  very  small.    When  the  incoming carbon slurry is clean
(i.e. it contains  only  the  carbon,  clean water and the adsorbed chemical),
the operating conditions can be very close to those used in solvent recovery.
A virtually complete recovery of the chemical is possible and  the incinerator
and scrubber may not  be necessary to the process.
System Functions

   The various functions the system is required to perform are addressed in
the following  paragraphs  in the  sequence  in which  they  are  performed.

Carbon Feed—

   The spent carbon  is delivered to the  system as a 5% to 30% carbon-water
slurry.  To reduce the water load on the regenerator, excess water is first
removed by mechanical procedures.

   Granular carbon slurvy  can  be extracted by transferring the slurry into
the feed tank which has provisions for drainage.  Drainage reduces water con-
tent to about 40%, or 60%  by weight dry carbon.  The drained carbon  is then
                                      12

-------


             fed into the  regenerator by  an  upward Inclined  screw feeder  that  allows
             further drainage during feeding.  .  •'.:' .
                                             • >'•** ,"'.-'
                For design purposes, the feed rate to the regenerator is:

                                 Carbon (granular) - 91 kg/hr
                                 Adsorbed chemical - 9.1 kg/hr
                                 Water             - 65.8 kg/hr
                                 Other adsorbates  - variable but small
                                 Silt              - variable, unknown

                Powdered carbon as  a  feed  would  consist of  10%  or  less  of  carbon as an
             aqueous slurry.  In order .".o make carbon  manageable in  a  screw feeder,  the
             water content of  the  mixture  would have  to  be  reduced from 90% to  60% or
             lower.  This can be done by centrifuging or filtering and drawing air through
             the filter  cake.  The dried centrifuge or  filter cake can then  be broken up
             and fed as  lumps into the regenerator.

                For design purposes, the feed rate would be:

                                 Carbon (powdered) - 91 kg/hr
                                 Adsorbed chemical - 9.1 kg/hr
 •                                Water             - 150 kg/hr
 ;                                Other adsorbates  - variable but small
 :                                Silt              - variable, unknown

                Details  on powdered carbon  feed are given here because evidence  from  MSA
 : "           work on carbon spent in tertiary sewage treatment (Juhola, 1970) showed that
 '            powdered carbons could  be regenerated in  a modified indirect-fired  rotary
 I            tube.
 >.
 i            Regeneration—
 (
 !.               The regenerator should perform the following  functions and  must perform
 t            the first three:
 r
 |               a.  Vaporize water from carbon;
 f
 |               b.  Desorb the  adsorbed chemical  if group 1,  2,  and/or 3;

                c.  Pyrolyze the  adsorbed chemicals if  group  4 and/or 5;
]
 f               d.  Deeorb group 1, 2, or  3 with minimum loss in recovery  and  pyrolyze
 i                   group 4 or 5  in a mixture of  group 1,   2,  or 3 with group 4 or  5
                    present;  and
•
                e.  Reactivate  carbon with loss of carbon not over 10% or  activity  not
 f                   over  30%.

                Material  and  heat  balance  calculations  were made  for two   situations:
             (1) only group  1,  2  or   3  chemicals  are  present  and completely  desorbed
             (Table  2),  and  (2)  only  group  4 or  5  chemicals are  present  with  carbon
             reactivated  to 100Z original activity at  5% carbon weight loss  (Table  3).
                                                  13

-------
                         TABLE 2.  MATERIAL AND HEAT BALANCE FOR  GRANULAR  CARBON
                                   REGENERATION AND ADSORBATE  RECOVERY

                                                   INPUT
\
Material
Act. carbon
Adsorbate
Water
Steam sweep
AH= -1060 ral/mole
Propane
AH= - 21,700 cal/mole
Air

kg/hr
91.0
9.1
65.8
22.8
(22.8)
7.8
(7.8)
126.6
323.1
°C
16
16
16
104
16
16

Kcal/hr
• 	
	
_«~
832—j
13,457-J"
93,492
	 	 —
107,781
Heat %



13-3
86.7
	
100.0
                  Act.  carbon
                  Steam from carbon
                    AH= +1060 cal/mole
                  Desorbed vapor
                    AH= +2760 cal/mole
                  Steam sweep
                    AH= +1060 cal/mole
                  Heat loss, 10%
                  Propane flut: gas
                    N2
                    C02
                    H20
                      AH= +1060 cal/mole
 91.0
 65.8
(65.8)
  9.1
 (9.1)
 22.8
(22.8)
 OUTPUT

316
149

149

149
              316
              316
              316
                                           322.8
 9,551
 3,956
39,060
    302
13,910
 1,336
13,457
 8,064

 7,409
 1,109
 1,688
 7,510

107,352
 8.9
40.0
27.0
                                          24.0
                                                                                    99.9
                                                      14

-------

    For the adsorbate recovery  operation (Table 2), the  following  operating
temperatures were assumed to be  adequate to  accomplish the desorptlon of the
chemicals:

                    Heat Source	Temp.  (°C)

                    Base (ambient)                      16
                    Steam input                        105
                    Act. carbon output                 316
                    Effluent steam and chemical        149

    Based on  the  data  shown  in Table  2 and  the  assumed  feed  composition,
about 40% of the heat requirement is for water desorption and 27% for chemical
desorption.

    The heating requirements for regeneration  by desorption only can be met
by direct  heating  or  Indirect  heating.  The  means of  heating affects the
offgas flow, as shown in Table 3:

        TABLE 3.  EFFECT OF DIRECT AND INDIRECT HEATING ON GAS
                         FLOWS FOR THERMAL DESORPTION
                                             Flow (kg/hr)
                     Gas                  Direct    Indirect
Steam from carbon
Chemical desorbed
Steam sweep
Combustion steam
Combustion C02
Combustion No
65.7
9.1
—
12.7
23.1
98.4
65.7
9.1
22.7
—
— —
                  Totals                   209.0        97.5
    When the heating is direct, the offgas flow to the condenser is about 209
kg/hr.  Of this, 121.5 kg/hr are noncondensable CO2 and N£.  These gases will
continue downstream and carry with them considerable amounts of group 1 and 2
chemicals.  When group 2 chemicals are present, incineration becomes a neces-
sary next step  to  convert the chlorides along with  nitrogen and sulfur com-
pounds to a  form  that  can be  scrubbed out  ot  the gas  stream by  water or
caustic solution.

    When heating is indirect, the offgas flow to the condenser Is 97.5 kg/hr.
If the gas system  is devoid of foreign noncondensable gases, virtually all of
the chemical and water would be condensed with very little or no gas going to
the incinerator.

    When group  4 or  5 chemicals are present,  pyrolysis  and reactivation are
part of  the  regeneration  process.   Materials  and  heat  balance  for this
situation are shown is Table 4.  In this case,  because of higher temperatures,
a 45%  carbon  loss  is assumed.  The operating,  temperatures noted below were
assumed to  be  necessary  to  accomplish pyrolysis  and  carbon  regeneration.
                                        15

-------

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f.. 	

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TABLE 4. MATERIAL AND HEAT BALANCE FOR GRANULAR CARBON


Material
Act. carbon
Adsorbate (-CH2-)
Water
Steam for acct.
AH= -1060 cal/mole
Propane
AH= - 21,700 cal/mole
Air



Act. carbon
Steam from carbon
AH= +1060 cal/mole
Desorbed gas
(-CH2-)
AH= +2760 cal/mole
CO
H2
Free carbon
AH= +4800 cal/mole
CO
H2
Act carbon loss
AH= +4800 cal/mole
CO
H2
Excess Act steam
AH= +1060 cal/mole
Heat loss, 7.5%
Propane flue gas
N2
C02
H20
AH- +1060 cal/mole


.''•'••.--'' •
REACTIVATION
INPUT
kg/hr °C Kcal/hr Heat %
91.0 16
9.1 16
65.8 16
22.8 104 832—, g-9
(22.8) — 13,457-J
12.1 16 	
(12.1) — 145,656 91.0
199.0 16
399.8 159,945 99.9

OUTPUT
86 899 34,272 21.5
65.8 316 8,820-, 30.0
(65.8) — 39,060-J

(5.8) 	 8,820-,
11.4 316 857
1.6 316 1,462 ;

(3.3) — 8,870 ;
7.8 316 580 23.3 -
0.5 316 479 _ <

4.5 — 12,096 ;
10.6 316 781
0.8 316 680
3.8 316 504 ;
3.8 2,092—1
11,844-1 ;
'*.
154.2 316 11,592 _
35.8 316 2,520 25.1 ;
19.5 316 2,621
(19.5) — 11.592-1
402.3 159,542 99.9
16 " : . . i
i

-------
              ^Y-ft^P'?15?^^
                 '       '      "   "    •'  ' "-""--"•   •"-'  •'-   '  '--'   '"•""'  '   '
                       Heat Source    Temperature (°C )

                      Base  (Ambient)               16
                      Steam input                 105
                      Act. carbon output          899
                      Effluent gases              316

    In  this  case  per Table  4,  30%  of the  heat  requirement  is  for water
desorption and 23%  for  chemical  pyrolysis  and carbon reactivation.   It  also
assumes a 5% carbon loss.

    For pyrolysis  and activation,  as was  the  case  when desorption  was  the
only  concern,  the  heating requirements  can be met by  direct  or  indirect
methods.  The affect on the amount  of offgas  flows  is  shown  in  Table 5:

    TABLE  5.    EFFECT OF  DIRECT AND INDIRECT  HEATING ON  GAS FLOWS  DURING
                           PYROLYTIC  REGENERATION
                                             Flow  (kg/hr)

                 	Gas	          Direct   Indirect

                  Steam  from carbon          65.7      65.7
                  Chem.  decorap.  products
                    CO                       19.1      19.1
                    H2                         2.3       2.3
                  Act. carbon  loss (5%)
                    CO                       10.4      10.4
                    H2                         0.9       0.9
                  Excess steam                —        3.6
                  Combustion steam
                  Combustion C02
                  Combustion N2

                      Totals                  307.9     102.0

    When  the heating is  direct,  the  offgas  flow to  the condenser  is  about
308  kg/hr.   Of  this, 218 kg/hr are  noncondensable  gases  (C02, CO, H2  and
N2)  and will  pass  through the  condenser.   For ease of calculation, it  was
assumed that the gaseous  pyrolysis products reacted with  the  steam forming
CO  and H2.   in actual  practice, this happens  only  partially.    If  NOx,  SOX
or  chlorides  are  present in  the adsorbed  chemical,  these groups  would  be
partially emitted as inorganic  compounds.   An incinerator and  scrubber  are
needed  downstream to  strip them from  the  vent  gas.

    When  the  heating is  indirect,  the  offgas   flow  to  the  condenser  is
about  102 kg/hr, of  which 32.7  kg/hr  is noncondensable and  combustible  CO
and  H2.    Any  NOx,   SO* or  chlorides  would  be  partially  or  completely
decomposed to release either  the inorganic  acid gas  or organic  decomposition
product which must  be further  decomposed  in the incinerator.
                                      17

-------
    Powdered  carbon  will have  a  water content over  twice  as large as  that
for  the  grsnular  carbons.    The  heat  requirement  will  be  correspondingly
higher,  but  both desorption  and  reactivation  will  require  much milder
conditions.   It can be expected that the regeneration condition  would not be
much greater  than those for  the  granular  carbons.   Powdered carbon is  not
often  used  in wastewater  treatment because-of high physical losses in air
and water streams.

    The  four  ways -of  carrying  out  the  regeneration  process  will  have  a
bearing on  the size  of tha  condenser and  other components  downstream of the
condenser as  shown in Table 6.

            TABLE 6.  EFFLUENT  GASES FROM  REGENERATORS OPERATED
                         UNDER DIFFERENT  CONDITIONS

Mode                        Process            Condensable    Noncondensable
                                  	(kg/hr)          (kg/hr)

 1             Direct heat, adsorbate                                                      ri
               pyrolysis  and carbon                                                        M
               reactivation                        86.2            222.3                    j.;
                                                                                          i:
 2             Indirect heat,  adsorbate
               pyrolysis, and  carbon
               reactivation                        68.0             31.8

 3             Direct heat and adsorbate           86.2            121.7
               desorption only

 4             Indirect heat and adsorbate
               desorption only	95 .3	nil	

    Gases from nodes 1 and 2, pyrolysis  and reactivation, leave  the
.regenerator at 315°C  and  those  from modes  3  and 4  at  about  149°C.  For
powdered carbon,  the  condensable input  rate  to the  condenser would be over
150 kg/hr,  primarily water.

Indirect Fired Rotary Kiln—

    The most favorable conditions for spilled  chemical reccvery/detoxificatlon
and control of air and water  pollution appeared to  lie with an indirect  fired
regenerator.   With indirect firing,  the  combustion  gas;s  are not contaminated
by the adsorbate or its decomposition products and thus r?r be emitted directly
to the atmosphere (assuming  propane  or  other  clean buvning  fuel) without
further treatment.   The contaminated- gas  stream  onslsts only of desorbed
materials,  steam  and a  small  volume  of sweep gas (whic'n may be  steam or flue
gas).  This allows  recovery  by condensation  and incineration/scrubbing of a
small  volume of non-condensibles  or, alternatively, incineration/scrubbing  of
the total stream  with minimally sized  equipment.


                                       18

-------
   Indirect fired  rotary  kilns  are employed  in a  variety  of  industrial
operations and design data are readily  available.  The major design criteria
are the kiln  areas  and  volume required for efficient heat transfer and the
solids loading, as percent of total volume.  In industrial practice, volume
loading ranges from about  2 or 3% to perhaps as  high as 15%, depending on the
moisture content and flow properties of the solid being handled.  Based on
experience with rotary tube regeneration,  a loading of 10% appears feasible
for granular  carbon  having  a  drained  moisture  content  of  about  40%.

   At 10% loading,  the  minimum size of rotary kiln  that could handle both
regeneration and activation of 91  kg/hr carbon (dry  basis) would be a tuba
of 0.6 m inside diameter with a 4.6 in heated length.  From..discussions with
manufacturers of this type  of equipment,  it was  estimated  that  a complete
kiln of this  throughput  would have overall dimensions  of 2.1 m  x  2.1 m x
10.7 m and would weigh approximately 22.7 kkg (25 tons).  Estimated minimum
delivery time was about one year.

   This is  both too heavy  and  too  large  to  fit on  the  semitrailer and
still leave work space and room for the other components of the system.  It
was apparent that either the regeneration rate would have to be drastically
reduced from the 91 kg/hr rate or chemical recovery would have to be sacri-
ficed.  Since the primary objective is to  reduce  environmental damage uti-
lizing carbon adsorption the correct decision appears to be to maintain the
regeneration rate  level  as  high  as  possible.   (Chemical  recovery  is  of
secondary importance).

Direct Fired Rotary Kiln—

   Direct fired  kilns  can be  operated at  higher throughputs than  can be
attained with  indirect  fired units of similar dimensions  because  of more
efficient heat transfer.  For this  reason, direct fired kilns have  more sizes
and designs commercially available.

   Two quotations were obtained from a  well known manufacturer; one for a 91
kg/hr (dry) carbon and one f  c a 45.4 kg/hr carbon  system. Both are packaged
systems consisting of the rotary kiln proper, dewatering feed screw, after-
burner, offgas  scrubber,  and quench tank.  The smaller  kiln  with a 380 mm
inside diameter refractor>-lined tube 3.80 m long, appeared capable of being
fitted onto a semitrailer with all the other required equipment.

   In view of  the  space limitations, the  smaller  (45.4  kg/hr) direct fired
rotary kiln was selected as most appropriate for further analysis.

Incinerator—

   Noncondensable gases entering the incinerator ov afterburner are heated to
760° C for 0.5  sec in an oxidizing atmosphere.  The size of the incinerator
can vary considerably depending on the  regeneration processes  used upstream.
Of the 222 kg/hr of noncondensable gases produced in mode 1, about 15% will
be combustible  gases, consisting of spill  chemical, CO and U2«  Of the 31.8
kg/hr, mode 2,  most is combustible with a high percentage of CO and H£.  Of
the 121.7 kg/hr, mode 3, only  about 3% will be combustible gas.  In  each case,
                                      19

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air with or. without  supplementary  heating is required to  raise  the tempera-
ture to 760°C to oxidize the gases<

   Table 7 gives  estimates  of total  final  gas volume in  the  incinerator at
760°C STP  and  anticipated interior  volume  when residence  time  is  0.5  sec.

              TABLE 7.  INCINERATOR SIZE ESTIMATES FOR 0.5 SEC
                          RESIDENCE TIME AT 760°C

Process
No.
1
2
3
Gas Volume Incinerator Volume
m^/min m^/min
at STP
13.3
5.0
2.5
at 760°C
50.4
19.0
10.7
m3
0.4
0.2
0.1

   In calculating  the  gas  volumes  for modes  2 and  3,  it was  assumed that
about one half  of  the  desorbed  chemical passes through the condenser because
of the high  volume of noncondensable  gases.  For heating calculations, the
desorbed chemical  was assumed  to  be  composed of  -CU2~  groups.   In each
process, it  is  also  assumed that enough combustibles are present to make the
incinerator  self  supporting,  i.e.,  no  supplementary heat is  required, even
if the  incinerator  has  to  operate  at temperatures  above  760°C.  At the
postulated temperatures  and  0.5 sec  residence  time, it  is expected that
well over 90%  of  the gases will be decomposed to C02 and H^O,  and HC1, N02,
and SC>2 if chlorine, nitrogen, and sulfur are present.

   The probable amount of  CO2  emitted from each  mode,  assuming  50% of the
organics in  modes  1 and 3 are condensed out, will be as follows:

                        Mode  1-82.1 kg/hr
                        Mode  2 - 46.3 kg/hr
                        Mode  3 - 37.2 kg/hr

Scrubber—

   The combustion  products  from the incinerator are passed through  a  scrubber
containing water  or a 20% caustic solution to remove  any  UC1,  NO,  502 or
other acid gas  present.  The  gas volumes entering the incinerator will  be as
given in column 2  or 3 in Table  7.

TASK II - PRELIMINARY  SYSTEM  DESIGN

   Design studies  were concentrated  on a  direct  fired  rotary  kiln system.
The preliminary design calculations for  carbon regeneration/activation were
based on a system  throughput  of 45.4 kg/hr  (dry regenerated carbon),  assuming
5% carbon loss in  processing.  The carbon feed was assumed to have  an average
moisture content  of  40% and an adsorbate loading  of  0.1 kg per kg  of carbon.
A commercial kiln designed to  handle 45.4  kg/hr  of  carbon  for sugar  puri-
fication was used  as the  basis  for  design.  By  modifying  the equipment
arrangement, a  suitable  spatial arrangement  was devised to  allow trailer

                                     20

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mounting.  A  schematic of  this  arrangement  Is  shown In  Figure  2.   The
Incinerator Is  mounted directly  above  the  kiln  tube for  space  saving.

   Calculations based  on the  capacity  of the  kiln tube size (380 mm inside
diameter (ID) x 3.80 m length) would  Indicate  the  feasibility of handling
more than 45.4 kg/hr of granular carbon.  Heat transfer considerations may,
however, limit  operation to  near design  capacity.  Availability  data  on
direct fired heat transfer are not sufficient to allow accurate prediction.
Major factors  such as  initial  moisture  content  and  ease  of  regeneration
(final temperature  requirements)  will  significantly  affect  throughput.

   A rotary  tube of  380  mm by  3.80 m  long  will provide a holdup In the
range of 10 to  15% of tube volume, and  retention  times  in  the range from 0.5
to 0.75 hr.   Previous data on  granular  carbon  regeneration/activation in-
dicated these  retention times  are  sufficient  for  complete  reactivation.
Retention times and holdup can be varied  however  by  adjustment  of  tube slope
and rotation rates.

   After the kiln size and system layout were defined, regeneration/activa-
tion process design calculations were  completed for several different cases
of operation of a direct fired rotary kiln.  The calculation summary for two
of these cases Is given in Table 8.  The major  factor in process requirements
and sizing of downstream components  (incinerator, etc) is the physical form
of the water  required to cool the hot furnace  gases and  provide steam for
activation.  Lower fuel requirements,  gas velocities and gas flow rates are
achieved by Injecting  liquid  water  rather than  steam.   Both heat of vapor-
ization and the sensible heat of the steam can be utilized.

   Case I  conditions, liquid water  injection,  were selected  for continued
design development.  The incinerator required for treatment of  the kiln off-
gas at  982°C and 0.5  sec  residence time  was calculated to be 0.23 m3 in
volume, 305 mm  inside  diameter by about  3.4 m long.

   Manufacturer's data on  lightweight,  high  temperature  Insulation  were
reviewed and  kiln tube weight  tradeoff  calculations  were  made.  Alumina-
silica fiber  insulation with desirable  heat  transfer  and mechanical prop-
erties Is  available  in  both  standard  and custom  fabricated  shapes.  At
a bulk density  of 0.45 g/cm^, this  Insulation provides considerable weight
savings over clay-based refactorles with densities  of  the order of  2 g/cm^.
A 76 mm layer  of this type of insulation enclosed  within a 457 mm diameter
steel pipe was  estimated as being adequate to  insulate  and allow mounting
the incinerator above  the kiln.

   Using these  design calculations  along with  weights  of  the  supporting
equipment, a  weight analysis was made.   The  values employed  are given in
Table 9.  The total  weight  of 42,185 kg is clearly in excess  of  the 33,113
kg trailer  limit  for over  the  road  operation  without  special permits.
Consequently, the design  was reviewed to find  areas where weight could be
reduced and/or  eliminated.   These areas were identified  as the kiln feed,
the scrubber  and  kiln  barrel  accessories.
                                     21


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                IO
y
                                                                                     8
1
2.14m
1
' - 1
3
GG

5

f
b

9^^^X ^^^ ^^^/ J"^
II 12 13 14
16
i 10 i LJUU
R7m - 	 .1 , .,_ .. , .
                                                         Equipment
                                  I.  Generator (electric)
                                  2. Slurry pump
                                  3. Dewatering screw
                                  4. Cond water pump
                                  5. Kiln
                                  6. Quench tank
                                  7. Elevator
                                  8. Dryer
                                  9. Screener
10. Panel board
II. Steam generator
12. Still
13. Scrubber
14. Scrubber pump
15, Still feed pump
16. Transfer pump
17. Transfer pump
                                                                                                          17
                                    Figure  2.   Mobile  Regeneration  Unit  (45.4 kg/hr Carbon).


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                   TABLE 8.  PROCESS CALCULATION SUMMARY*
                                     Case I                      Case II
     Item                        offgas at 315°C             offgas at 315°C
                                   water added                 steam added
Propane Required, kg/hr               10.8                        40.2

Inlet Gas Velocity, in/sec              2.7                        13.7

Heat Load, kcal/hr                 129,600                     485,000

Offgas Flow Rate, m3/hr                606                       2,566

Offgae Velocity, m/sec                 1.5                         6.2

Steam or Water Added, kg/hr           49.0                         420
*Basis: 45.4 kg/hr carbon output; 2.3 kg/hr carbon loss; 4.5 kg/hr adsorbate;
        40% water content in feed; activation temperature 899°C; kiln furnace
        temperature 1093°C
                                     23

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                TABLE 9.  ESTIMATED WEIGHT FOR MOBILE CARBON
              REGENERATION UNIT WITH DIRECT FIRED ROTARY KILN
      Item                                                  Estimaced Weight
  .                         	                               (kg)


Diesel Generator, 50 KW                                          1,814.4

Rotary kiln, 380 mm (I.D.) x 457 mm (O.D.) x 3.80 m (Long)      11,340
  Dewatertng feed screw
  Afterburner/Incinerator
  Offgas scrubber
  Carbon quench tanic

Process Equipment                                                5,443.2
  Elevator dryer
  Screener
  Auxiliary scrubber
  Still
  Pump (5)
  Control panel

Misc. Equipment                                                 11,340
  Steam generator
  Holding bags and hose
  Trolley hoists and winches
  Lighting and ventilation
  Piping (material)
  Fire and safety equipment
  Special framing, walkways, etc.
Tractor
Trailer, 13.7 m long

  Total
 7,257.6
 4,989.6

42,184.8
                                     24

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                  The  initial kiln feed system proposed  for handling slurries or wet  feeds
               employed a dewatering  screw  feeder.  Consideration  of  potential field  sit-
               uations, volumetric feed rates,  and granular  carbon drainage rates,  showed
               the possibility of  completely eliminating  the requirement  of a  dewatering
               screw feeder.   The  initial  draining of  the  carbon  feed  could  be  achieved
               external to the trailer  mounted system.   The drained  carbon could then  be
               transferred to a feed system on the trailer.  This would  consist  simply of a
               feed hopper and associated feed screw  to transfer the  drained carbon  to the
               kiln.  Model  studies  indicate  this modified  hopper and feed  screw  would
               extend only about  1 m beyond the feed housing  of  the kiln versus  3 m for the
•               dewatering screw.
\
I   j               An investigation of the jack arrangement  which provides adjustment  of the
>   i            kiln barrel slope  was made,  with  the  decision that  it could be  eliminated.
               The nominal slope had  been set  at  208 cm/m with  adjustment  possible  both in
               slope and speed to  vary  conveying  rate.   The  analysis showed that  sufficient
               variation could be provided by the adjustment of rotational speed alone, with
               some adjustment possible by shimming the channel supports.
                  A design review was also made on the  scrubber  water system to investigate
               weight savings.   Ion  exchange treatment  of total  process  makeup water  was
               considered first but  exchange  resin  requirements  were deemed  to be  prohibi-
               tive In both cost  and size,  The design  selected  employs  continuous caustic
               treatment and filtration  of all makeup water, with scrubber  recycle through
               an air-cooled  heat  exchanger  to  minimize  makeup  requirements.   Process
               calculations considered both  normal  and  anticipated maximum  water  require-
               ments.  Maximum makeup  water  required  for the kiln and scrubber system is
               8.3 1/min.

                  Caustic treatment  of  both  makeup water and  scrubber  recycle and  waste
               streams will  require a maximum of  45  kg/day  of  NaOH  or  30  I/day  of  50%
               caustic.  This assumes  a  maximum acid gas  formation (as HC1) from adsorbate
               incineration.  Normal  operation  may produce  less  acid  and lower  caustic
               treatment requirements.   Additional  water makeup  is  required   for  product
               carbon cooling.   Wet processing  of  the product  increases the  total  water
               makeup requirements to  19 1/min.

                  Changes in  the three  areas noted plus  a  variety  of small modifications
               enabled a  reduction in the estimated equipment  weight  to  18,144 kg.   This
               allows for  a  standard  trailer configuration  without the  need  for  special
               operating permits.   The  final design and spatial  arrangement were  as  shown
               schematically in Figure 3.

               TASK  III - BENCH  SCALE STUDIES
   s
   !               A  number  of the  decisions to be  made  in  the delineation of the system
   '            design depended on an  understanding  of  operating  requirements.  To provide
   j            this  particular data, a series of studies were conducted using the laboratory

   i
   •i
                                                      25
fr

-------
.  2:
:.  d
•  O
•-  rn
•  to
'  X
.  m
•,  m
••  H
     5 >  !



     fl!
     :•* w
     r 1  i
     -< a
     n k  i
         .
        0 f
        •s
                ro
                o>
              A. ROTARY  KILN

              B. INCINERATOR
              C. SCRUBBER-LIQUID COOLER

              D. CARBON FEEDER
                                                Figure 3.   Trailer design


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scale regeneration unit built during the  earlier  EPA program.  These studies
had two objectives:  an evaluation of the regeneration/incineration design of
the proposed mobile  unit, and the  testing  of certain  proposed  materials  of
construction under simulated conditions.
Bench Scale System

   The design and operational  characteristics  of the laboratory-sized regen-
erator are given in the final report, "Laboratory Investigation of the Regen-
eration of Spent Activated  Carbon" (Juhola,  1970).   The unit was built as an
indirect fired  system.   The  regenerator  is an  electrically heated  rotary
(stainless steel) tube 82-5 mm  in  diameter with a 1080 mm heated length.  An
auger type  volumetric feeder  is used  to  meter the  carbon  into  the  rotary
tube.  To  approximate  the  direct  firing  characteristics  of  the  proposed
regenerator/incinerator, a  countercurrent  flow  of  gas  was added  to  the
laboratory unit to simulate the products of propane combustion.

   The laboratory  regenerator   operates  at  18% loading  with a  .590  kgm/hr
(regenerated) carbon  throughput.   The exhaust   gas  cleanup  train consists of
a thermal incinerator,  an air-cooled condenser, and  a water spray scrubber.
The thermal incinerator  is  designed to  operate at  900°C, and gives a 0.5 sec
residence time to the effluent gas from the regenerator.  It is heated with
natural gas at startup,  the flow of which is reduced as the concentration of
desorbed flammable products increases and  comes to  a steady-state flow rate.
Air input is metered  to maximize combustion efficiency.

   The condenser is  a finned  tube  and  gives about  0.5 sec  residence time to
the gases from the  incinerator.  Some 25 wt %  of  the gas is water vapor and
separates from the  noncondensable   gases,  N£ and CC>2,  in the scrubber.  The
condenser reduces the heat  load on the scrubber and minimizes the amount of
scrubber liquid  which  needs  to   be  recirculated.   The  cleanup train  is
arranged for  operation  with  or without  the  scrubber  or   condenser  in  the
train.  In this  way, data  can  be   obtained  on various  alternate  routes  for
exhaust gas cleanup.

   The C02,  N2»  air  and part  of the  gas  stream are  metered in to simulate
the products  of combustion of propane in  air.  Extra steam is  added  by a
steam generator  to  simulate  moderation  of  the  flue  gas  temperature.  The
water from  the  carbon and most of  the  chemicals  are  desorbed  before the
carbon reaches  the  hot  zone  of  the rotary  kiln.   This   mixture  of  input
materials approximates  the  proportions  that   will  be  seen  by  the  mobile
unit.
Chemical Classification and Selection

   Evaluation of  the regeneration/incineration  capabilities  of the proposed
mobile system  required the selection  of representative  chemicals  from each
of the  five  categories  previously  identified.   Each  group  has  specific
properties which effect its behavior in  the thermal cycle.
                                       27

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                For each  of  the  five groups  of spill  chemicals, representative materials
            were chosen  for  study in the  bench scale  rotary kiln.  The following are the
            selected  test chemicals  for each group.
Group
1
2
3
4

5
Representative Chemical
Methyl acetate
Die hlorome thane
Diethyleneglycol diethyl ether
Benzenesulfonic acid
Hexamethylene tetramine
Tris(2-chloroethyl) phosphate
Mol . Wt . (g/Mole)
74
85
162
158
• 140
277
\
'.        .    Regeneration/Incineration Tests

!                Regeneration runs  were made  with  each  of the  five materials.   Three
            consecutive runs were made  on  each  of the chemicals except for hexamethylene
i            tetramine, using  Pittsburgh CAL  carbon.   The  hexamethylene  tetramine  runs
i            were not completed because of corrosion problems in the incinerator.

                In  preparing  the  spent carbons  for the tests,  the carbon  was  treated
{            with  10% by  weight  of chemical  and 50%  by weight  of water.    For  water
!            soluble  materials the  additions  were made  as aqueous  solutions.   For water
i            insolubles,  the  chemical was  added first and then  the  water.   In each case,
j            the mixture was  allowed to  stand  overnight to  allow equilibration  of  the
            chemical with  the  carbon.

                For  the dichloromethane  runs,  the  feed rate  was  1.26  kg/hr,-giving  a
            residence  time of 45 minutes  and a volumetric  loading  in the  rotary tube of
            about  16%.   When  the necessary  flows of N2,  002.  02 and steam  to simulate
            direct  firing  were  fed to the rotary kiln,  the  gas velocity was  such  that
            considerable   quantities  of  carbon  dust  were carried  downstream  to  the
            incinerator  and  scrubber.  In  the  runs  for  the other  chemicals,  the  carbon
            feed  was decreased  to  0.72 kg/hr, giving  a volumetric  loading  of about  9%
            for a 45 minute residence  time.   This  alleviated  the  problems  generated by
            carbon dust carryover.

                Satisfactory  results were  obtained i-n all test  runs.   The  methyl  acetate
            and  dichloromethane  were  completely  decomposed  on  passing  through  the
            incinerator.   The  incinerator  was  found to  operate best between  816°C  and
            871°C with  an  air  flow  of 18 1/min.   The HC1 formed from the  dichloromethane
            was removed from  the gas  stream  along with  the steam  condensate  by  the  air
            cooled   condenser.   The   scrubber   was  not  used  in   these  tests.    HC1
            concentrations in  the  condenser  effluent  gas  stream  ranged  from 10 to  60
            ppm.

                Similar  tests  were  carried  out  for   the  other  chemicals.    Typical
            concentrations of gases  from  the regenerator  and  scrubber  for  each  of  the
            other  test  chemicals are given  in  Table 10.  Some  fog appeared  in the  vent
            gas  for the  benzene sulfonic  acid  and tris(2-chloroethyl)phosphate  runs.
                                                  28

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                     TABLE 10.  TYPICAL CONCENTRATION  OF  GASES  EXITING FROM THE
                              LABORATORY  SCALE  REGENERATOR AND  SCRUBBER
                                                      txic  bas  concentration
                                                                            (ppm)
               Test Chemical
                                                  Regenerator
                       Scrubber
            Benzenesulfonic acid
            Diethyleneglycol diethyl  ether
            Tris(2-chloroethyl)phosphate
CO - >2000
HC*- >2000
S02 ~ >400
H2CO -  30
CO - 4000
CH3COOH - >1000
H2CO - 100
CO ->4000
HC1 - 300
NO - none
CH3COOH - 27
CO - 50
HC - none
H2CO - none
S02 - 30
H2CO - 5

CO - 35
CH3COOH - none
H2CO - none
NO - 6
N02 ~ none
CO - 45
HC1 - 90
                                                                                - 24
j
            *HC = Hydrocarbon
                                                  29

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                                 r^fv~VV™^'*vSf^,"?^^^^^y3?W^y^**^^^^*\w^^
Apparently  the S02  and HC1  are  difficult  to  remove  completely,  and  they
result in acid mist  formation.                                .    ,

    The  carbon  yields were  about  97%  and  a  slight   increase   in  density
occurred.   The conclusion  is .that  the  type  of mobile  unit  being designed,
when  operated  under   the  planned   procedures,  should  give  satisfactory
results.

Materials of Construction

    The  principal  item of concern in the regenerator design was  the thermal
insulation  for the  kiln.   The  system requires  a  high  efficiency ceramic
insulation  which  can  withstand  the  anticipated vibrations  of over-the-road
travel as well as  the  heat  and  abrasion of  the regeneration operations.

    Extensive   discussions   with  insulation   manufacturers  led   to   the
conclusion  that  only  silica-alumina  fiber  refractories  could  provide  the
combination  of properties  required.   Samples  of  other materials  and  forms
were  tested.   Alumina-silica coated with  a hard  surface proved  to be  the
best  but it was  ultimately found that  this  refractory could not withstand
the  direct  loading  of the wet  carbon.   For  this  reason,  the  design  was
changed  to provide a metal  liner in  the tube  to protect the insulation.

    The  final step  in this  task evaluated  material  requirements  for  the
liners  in  the kiln  barrel  and  firing  breech.  The basic material selected
was,  300 series  stainless  steel.   Since  some material  problems  had  been
experienced  in the  hot  corrosive sections of the laboratory unit, Inconel
601 was  chosen for those  areas  in the mobile  unit.
                                      30

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                                      "    "   -•     ""'           '   '  ":'   ""  ""'  "
                                 SECTION 4

               PHASE II - COMPONENT SPECIFICATION DEVELOPMENT
   With completion  of Phase  I, the  basic system  configuration had  been
delineated, the performance requirements of each  system  component had  been
defined, and  weight  and  size  limitations  had  been  established.  Taken
collectively, these activities  allowed the conclusion  that  a mobile  carbon
regeneration system  could  be  assembled  successfully,   incorporating  an
onboard incinerator and  scrubber to handle  the materials stripped  in the
regeneration process.

   The next step  in the  process was  the  preparation  of detailed  specifica-
ions for each  component and  subassembly.  This effort was  initiated  with
the understanding  that  commercially  available  equipment or modifications
thereof would be specified wherever possible.

   During the proposal stage and the early tasks of this program,  the intent
had been  to modify  an  existing  thermal  treatment  device  for  the basic
regeneration unit.  As  the program  progressed  it became clear that  this
would not be possible.  The requirements  and limitations established for the
rotary kiln, the incinerator and the scrubber were found to  be  outside the
manufacturing limits of commercial suppliers.  Thus,  the  first task in  this
phase was the development of a detailed design and manufacturing specifica-
tions for these three key items.

KILN

   The kiln specifications  had  been  set  by the results  of  the  laboratory-
scale test program and the program goals.  The principal  factors were a  45.4
kg/hr throughput  based  on  dry  regenerated  carbon  weight and  a final
regeneration temperature of 982°C.   With this  starting  point, a series of
design calculations were made with the following results.  For a 45.4 kg/hr
recovery of dry  regenerated carbon,  the  input will be 54.4  kg/hr  of spent
carbon together with 4.5 kg/hr of  adsorbate and  36.3 kg/hr of water.  Carbon
losses will  be  2.3 kg/hr due to  burnoff and 6.8 kg/hr  as  unusable  fines.

   A temperature  profile was constructed within  the kiln barrel,  starting
with 100°C  in the  initial  drying section and  increasing to 982°C  in the
final regeneration stage.  These temperature  choices  are based upon  a 1093°C
temperature for  the tempered  burner  gas.  Maximum temperature in the liner
and firing breech was set at 1038°C with  a  1260°C  design temperature for the
liner insulation.  Maximum  outside shell temperature was set at  93°C which
requires &  731 Kcal/hr-m2 heat  loss.
                                     31

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       •  -"• I	•''..'   * .' '  "'' •      "     "'•','•"••-..•"•-,-' .••••"•'-'.••••,', 5 .':•*,•-- '.•••-;• •• ..  '•*''•'••   "'  "jja/'j
    Baaed upon  these  requirements  and  experience with  the laboratory  unit,
 materials of  construction  were  selected.  Carbon  steel was  chosen for  the
 majority of  components.   For  most  of  the elevated  temperature components,
 low carbon  304  and 316  stainless  steel  were  specified.   Inconel  601  was
 chosen to  provide greater  high  temperature strength  for  the hottest  region
 of the kiln.

    The kllr.  is  a three  stage  rotary  barrel  with  carbon  flowing  in  one
 direction and  hot gas  in the opposite direction.   Countercurrenl"  gas flow
 provides for  efficient heat  utilization.  In  the  first   stage,  wet   spent
 carbon is cascaded by lifting flights into  the hot gas stream.  The contained
 water and  low boiling  adsorbates  are  removed  here.   In  the  second  stage
 increasing temperatures are encountered which vaporize the remaining adsorb-
 ates begin thermal  decomposition of some  species.  In the  final stage, car-
 bon is gently  tumbled  and the temperature  is raised  to  the maximum of  982°C
 to complete regeneration.

    To achieve  a  process  flow  of  45.4  kg/hr of  dry  carbon,  a kiln barrel
 size of 371 mn inside diameter and 3.9 m long was calculated to be necessary.
 A slope of 0.6 cra/m and a rotational  speed  of 5 rpm at an  11.7Z kiln loading
 gives the desired throughput.   This is a 0.14 m3/hr feed with a calculated 22
 mln residence time.  The  design  operating  parameters  are  tabulated  In Tabl-a.
 11*

    The major concern  with the 'iiln  was the thermal  insulation.  It  must be
 lightweight, resilient, and have  a high  maximum temperature  along with a
 high K factor.   Originally it  had  been   Intended  to  use a  ceramic  kiln
 interior,  but  laboratory-scale   testing made  it  clear  that  no  available
 material  could provide  the necessary insulating  properties and still  with-
 stand  the  abrasion and mechanical  stresses  which would be  imposed.   A metal
 inner  barrel alleviated some of these problems.

    The anticipated road stresses eliminated all  of  the normal rigid  case  or
 molded Insulating media.  Alumina-silica ceramic  fiber forms  were  Identified
 early  in  the program as the most promising material.  Evaluation of  commer-
 cially available  materials resulted in choosing Kaowool  for the  kiln Incala-
 tlon.   This  was  available  as  vacuum  formed  cylinders  with  a  7.25  kg/m3
 density.  Based  on  its  thenaal   ratings   and  the  kiln  characteristics,  a
 minimum thickness of  114  mm would  be required to  maintain the 93°C design
 shell  temperature•

   The  basic  kiln must  be  fitted  with several accessory  Items for operation.
 A feed  unit  is needed to  deliver  spent  carbon to the  firet stage  of  the
kiln.  A  4  hr  operating  supply  was  chosen  as  the  design  point,  which
 is equivalent  to  0.57 m3  of  product.  A  feed  system  waa chosen  with  an
 appropriately sized  hopper and a dual pitch screw feed.  A 58 mm pitch was
chosen to  meter  the  carbon from the hopper  and a  76 mm  pitch to  provide
movement through  the transfer  tube without plugging.   An  adjustable  drive
was added  to  allow  delivery  rates  between  0.06  and  0.28  m3/hr   of wet
dewatered carbon.   The  feed  system  used  300   series  stainless   for all
components In contact with  the wet  carbon.
                                      32

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              TABLE II.  KILN DESIGN OPERATING PARAMETERS
   Parameter                 Identification                        Value


   Flowrates      Carbon content of spent feed                      54.4
    (kg/hr)       Adsorbates vaporized                               4.5
                  Residual water vaporized                          36.3
                  Carbon burnoff                                     2.3
                  Carbon fines                                       6.8
                  Carbon product recovered                          45.4
                  Fume gases to incinerator                        272.2


        Fuel      Propane @ 1.3-2-psig                               9.1
     (kg/hr)      Air @ 2-12% excess                             150-168


       Steam                                                       32-54
            	;	


    Pressure      Water Vacuum, @ Firing Breech                  3.0-3.8
      (mm)


Temperatures      Ambient feed                                        21
     (°C)         Initial drying section                             100
                  Final regeneration section                         982
                  Liners @ firing breech                            1038
                  Tempered burner gas                               1093
                  Liner and insulation rating                       1260
                  Fumes to incinerator                               204
                  Shell, @ 731 K cal/hr-m2                            93
                                   33


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   At the other  end of  the  kiln,  a product  recovery system is  required to
collect the regenerated  carbon.  This  unit must cool  the  carbon,  remove the
unusable fines, and discharge the regenerated product.

   Cooling is  best  accomplished by  water quenching.  Further,  it  can  pro-
duce a  slurry which  is  an  effective  form for  both pumping and  separating
into size fractions.   The  selected design  was  a quench task using  recircu-
lated water.   The  slurry formed,  normally about  7% solids, is pumped  to  a
two deck  screening  separator.   An  air  cooler was  incorporated to  insure
adequate cooling before  entering the separator.  Carbon  material larger than
40 mesh is removed  in  the first  stage  for recycle.  Fines  less  than  325 mesh
are separated  in the  second  stage  for  disposal.  The effluent  is filtered to
remove all participates  greater than  10  u and  recirculated  to  the  quench
tank.

   A slurry pump  (Moyno) was  selected to provide  a flow of 0.6-0.9  m/sec.
This was a compromise to provide high enough flow to prevent  particle sepa-
ration and plugging but  below the  rate which would cause exaggerated erosion
of pipe and containment components.

   The kiln  is  also  fitted  with  a   variable  speed drive  which  permits
adjustment of  rotation between  1 and  10 rpm.   This  allows variations  in the
residence time which  might  be  necessary for carbons with  high  loadings or
difficult to remove adsorbates.

INCINERATOR/AFTERBURNER

   Incineration of  the  offgases   from the  kiln had  been  selected  as  the
most appropriate mechanism  for detoxification  and disposal of  the desorbed
contaminants•  The  gases would  enter the incinerator from the kiln through a
fume breech.

   The initial design parameters  were based upon a  nominal  fume  inlet of
272.2 kg/hr effluent  gases  of which 4.5 kg/hr would  be  adsorbates  or their
decomposition products.  Calculations  gave  1.0  sec  as an  adequate residence
time for mixing with burner gas and combustion.

   For this rasldence, the  firebox  was  sized  at 0.61  m x 0.61  m x  1.5 m
long.  The associated  burner was sized to provide up to 126,000 Rcal/hr using
11.3 kg/hr of propane and 227 kg/hr of air.   These  are  maximum values, all
components can be varied to  achieve  efficient combustion,  based  on stack gas
composition.

   The incinerator  is  designed  so  that fume gases enter  below the burner to
achieve good  mixing.   The design fume  inlet temperature  Is 204°C with a  flue
gas outlet temperature of  982°C.   The  same temperature,  982°C, is the design
temperature for  the   insulation  hot  face.   The  outer  shell  temperature
maximum is 93°C.

   The hot side  of the  incinerator  is  Inconel 601 to assure  adequate  cor-
rosion resistance and hot  strength.   For  insulation, alumina-silica Kaowool
was chosen.   A 3.63  kg/m-*  density wrap-around  blanket  form was  deerood the
                                      34

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best choice with  a mineral  wool backup.   After consideration  of  over-the-
road stresses, an external  lever of ICaowool  board was added  for mechanical
strength.  The overall  insulation thickness was  set at  142 mm  in  a carbon
steel shell.

SCRUBBER

   Although the incinerator  is  the primary  means of degrading  the  offgases
from the kiln,  the  products of  combustion also may contain acid gases such
as HC1 and  SC>2, particulate matter, and  certain condensables.  To remove the
undesirable materials from the flue gases, a  scrubbing  system was felt to be
necessary.

   The scrubber consists of  five  components  —  a spray  tower, a caustic
scrubber, a  cooling  tower,  a  liquor   recirculator,  and  a  stack  blower.

   Flue gases  entering   the  scrubber  system are  adiabatically  quenched  in
the spray  tower,  passed through the  caustic scrubber  to remove  acid gases
and into  a packed  tower to  cool and demist.   The gases  venting  from the
packed tower  should  be composed primarily  of  C02,  N2,  and  02.   Through
monitoring of  these  gases,   changes  are  made  in  the  system,  incinerator,
and/or scrubber  to  correct  any deficiencies.   Vent  gases  are discharged
through a stack using a blower to maintain an induced draft.

   The reclrculating  scrubber  liquor  passes  through  a filter  to  remove
particulate matter,  through a  cooler for temperature  control,  and  into  a
makeup chamber  to provide  pH control.  The  scrubber design  parameters are
given in Table 12.

   Material selection   for  the  scrubber  system  was  made   principally  for
corrosion resistance  except for  the  spray tower  where  elevated temperature
strength was  required.   The  material  selected  for   the   spray tower  was
Inconel 625.   It  was sized at 406 mm diameter and  1.8 m high to accomodate
maximum inlet  gas  flow.   It   is  flanged  to   the  incinerator,   thermally
insulated and  contains  6 spray  nozzles  spaced  equally  around the circumfer-
ence.

   The tower  outlet discharges  to  a sump  of approximately  380 L (100 gal)
capacity.   Anticipated  operating conditions  would have  the sump two-thirds
full of spent scrubbing liquor.   The upper one-third acts as a duct  to direct
the quench  gases  into the caustic rubber.

   The caustic scrubber is  designed as a .61 mm diameter, 1.5-m-high cylinder
packed within  .15 mm of the  top with Pall rings.  The liquid distributor is
located above  the Pall rings.   The  scrubber is  vented  through  a  MSA mist
eliminator  using  Teflon fiber spirals.   The material of construction is fully
annealed low  carbon  316  stainless  steel to  minimize  the  possibility  of
chloride stress corrosion.

   The liquor  cooler is designed to  handle 151,200 Kcal/hr  (600,000  BTU/hr)
using ambient  air at 332 m-Vmin (11,700  cfm).   The  cooler is  located above
the kiln at roof  level  to facilitate  venting  the  cooling  air.
                                       35


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                    TABLE 12.  SCRUBBER DESIGN PARAMETERS
 Parameters
Identification
Value
Gas Flows                    Spray column inlet                         315
 (m^/min)
                             Packed column inlet                         15

                             Scrubber effluent                          8.4


Spray Water                  @ 50% vaporization          .               7.6
 (L/mln)


Scrubbing
 Liquor                      Scrubber inlet                             114
 (L/min)
                             Bleed pH stream                            7.7

                             29% NaOH addition                          5.7


Pressures                    Fan Suction                               106.
 (mm water
  vacuum)                    Scrubber outlet                            51.

                             Packed column inlet                        25.

                             Spray tower inlet                          23.


Temperatures                 Spray tower inlet gas                     1016
 (°C)
                             Packed column inlet gas                     84

                             Scrubber effluent gas                       66

                             Hot scrubbing liquor                        79

                             Cooled scrubbing liquor                     57

                             Ambient spray/caustic                       21
                                      36
                                 	
             ^

-------
    The scrubbing system  is  designed  to use available water with  an  onboard
supply of caustic.   Space and weight  are available to carry 757 liters  (a  7
day  supply)  of 20%  NaOH solution.   Although  water  would be  drawn from  a
local source, the onboard system contains a receiver  tank  with  a pressurized
reservoir.   This is  to  allow operation using adjacent water  sources  if  a
local pressurized supply  is  unavailable.

    Water  drawn  from  a  local  supply  is  discharged back to  its  source.
Activated carbon  filters  are employed  in  line to insure  acceptable  quality
for discharge.

REGENERATOR POWER AND CONTROLS

    The total system was  designed  to  draw power and gas  from  local utilities
if available.   Power requirements  were  estimated at  50 KVA.   To  compensate
for  peak  needs,  the  design value was increased to 75  KVA  using 240V  3-phase
power.

    The   gas  requirements   for  the   kiln  and  incinerator   combined   were
estimated  at  .025  x  106  Kcal/hr.   This is equivalent  to  1.3 m3/hr  of
propane.

     It is expected that operation  of  the carbon regenerator will  often be at
a  remote  site where  local   utilities  are  unavailable.   For this  reason the
system must  be capable of  independent  operation.  The  gas requirements can
be readily  filled by liquefied propane  trucked to the site.   The  11.3 m3/hr
of gas  is only 41.6  1/hr of liquid.   A 1.25  to  2 psi  pressure  is adequate
for  the. onboard system.

     The  electrical  requirements can  be met by an onboard diesel generator
unit.,  The  proposed  physical  arrangement allowed   sufficient  room  in the
forward   part  of  the  trailer  tor  a  commercial  unit   delivering  60  KVA
continuously  with a  peak output  to  75  KVA.    The  generator was  located so
that  the exhaust  could  be  ducted through the front of  the  trailer.   The
muffler  was  suspended  on  the  front  of the  trailer above  the   cab  of the
tractor.

     A diesel  fuel storage tank was provided below the trailer deck.  It was
sized for 1514 liters (400 gal) to provide 3 days of continuous operation.

     The  diesel  generator area was  expected to generate  sufficient noise and
heat exclusive of the.  exhaust system  that  a  soundproof  enclosure would be
required.  Therefore,  the  generator  enclosure was  acoustically  insulated.
To   maximize  space  utilization,  the  wall   of  the  generator ' enclosure
separating  it from  the main trailer area was used  as  the  support  for the
control  panel  of  the regenerator/incinerator.

      The  control panel contains the  necessary instruments and recorders for
operation  of  the  regenerator.     All  components   operated  at  elevated
temperatures  are  continuously  monitored  by  means  of  thermocouples.   Gas
flows, gas  temperatures, and effluent gas compositions are also continuously
monitored.    Water  temperatures,  water  flows,  and  pH   are  measured and

                                      37

-------
             recorded.   The diesel  generator  output  is  also instrumented.   Fail  safe
             interlocks are  provided  to  protect  against  runaway  reactions  or  other'
             abnormal operating conditions.  All  interlocks are connected  to  visible and
I             audible alarms.  Where  possible,  interlocks are also  connected  to automatic
f|            shutoff-shutdown operators.

U            TRAILER DESIGN
»j
•i               In the early  phases  of  the  program a decision had been reached  to base
[i            the trailer design on available configurations.   Complete trailer design was
i             felt to be beyond  the scope of this program.  The  basis for the development
',             was a standard enclosed platform  van 2.44 m wide x 13.7 m long x 4.1 m high.
IJ
':;               Four significant modifications  to the standard design were found
;,            necessary:
!i
I;                    (1)  To reduce  over-the-road  stress  on  the  regenerator/incinerator
ij                         unit and  allow  at  least limited  off-the-road  movement,  the
'i                         platform support was  strengthened and reinforcements were
\                          added to minimize bed deflections.

j.j                    (2)  The  sides  and  the  rear  of  the van  were  redesigned  so that
J                          they could   be  opened  for   ventilation   when  the  trailer  was
I                          positioned  for  operation.   In  the design  chosen,  the  sides
•                          are made in  two  segments.   The lower   segment  drops  down-  to
•i                         provide a walkway  on both sides.  The upper  segment  raises to
;{                         provide an   awning  structure.   Thus  along  with  ventilation,
|                          the design   improves   access   and movement   within  the  trailer
•                          and worker  protection during inclement weather.

                     (3)  A  separate access door  is  provided  for the diesel  generator
                          enclosure.   This  area  has  its  own overhead  ventilation port.

[                     (4)  A  series  of  jacks  are incorporated to  allow leveling  of the
                          trailer on sloped or uneven ground.

                In addition  to  the  above  modifications,  the  trailer  was  fitted with
             several systems  to accomodate  specific   components.   Included in  these are
             mounting supports  for  the  generator  muffler,  the  vent  stack  from  the
             scrubber, and  piping penetrations  through the  floor  for water,   gas  and
             electricity.  The  underside of  the trailer  accomodates a series  of tanks
             for water, diesel  fuel,  and caustic solution and the pumps  associated with
             each of these services.  The minimum road clearance  required for these units
             was calculated to be 368 mm.
                                                   38

-------
GENERAL REQUIREMENTS

     The unit  as  designed is completely telf-contained  for  field  operation.
It  requires  a  parking  area of  12.2 m by  24.4 m, a  local  source of  fresh
water, propane or natural gas, and  a source of  caustic  replenishment.   Power
can be drawn  from the  local utilities or from  its  onboard generator.   Also,
a mechanism is necessary  to  dewater  the spent carbon  and drums  are needed  to
receive the regenerated product.
                                      39

-------
                                          SECTION 5

                        PHASE  III  -  PROCUREMENT, ASSEMBLY, AND TESTING


           With  completion  of  the  design  phase,  the  acutal task  of  building the
        mobile regenerator  was initiated.  This  involved the procurement of  all of
        the required  components,   their  assembly,  the verification  of  system opera-
        tion  and finally delivery  of  the  regenerator to  the  Environmental Protec-
        tion  Agency.

        PROCUREMENT

           The specifications  prepared  in  the previous  design  phase  were  arranged
        in appropriate  form for  the preparation  of purchasing  documents.   For all
        possibile components   solicitation  was  for  existing  commercially  available
        equipment.  Where  minor differences existed  between requirements and avail-
        able  units,  the differences were resolved  in  favor of  the avilable equip-
        ment  where  possible.  Where modifications were  absolutely  necessary,   these
        were  negotiated with  suppliers.  Although  price was a  consideration,  per-
        formance was  the  major  factor.   Where  modifications  were  necessary, the
        design requiring the least revision was the  usual choice.

           In all  procurement and  equipment  selection  the  Quality Assurance   Group
        at MSA  was part  of the  decision procens.   They in turn verified  that all
        incoming components complied with specifications.

           In the  course   of  the procurement  process  some problems  with  incoming
        equipment were  revealed.    In  all  caces  the  difficulties  were minor and
        successfully  resolved  without  compromising  the  system design  or  operational
        specifications.

           These significant items are  as follows:

                 (1)  The  carbon  product separator  as delivered exhibited  unaccept-
                      able  blinding   (screen  plugging).  A  vibratlonal  antlbllnding
                      accessory was  Incorporated.    In  addition,  to assist  in  effec-
                      tive  separator operation,  a  9.5  mm mesh  basket  screen was
                      installed in the  slurry  tank.

                 (2)  The  spent carbon  feed  screw experienced some binding when the
                      carbon contained  an appreciable quantity of fines. Increasing
                      the pitch  of  the  feed  tube  essentially eliminated  this  diffi-
                      culty.   It  was recognized, however, that carbon  feed  had  to be
                      reduced  below   the  design level  to prevent plugging  when the
                      feed  contained a large percentage  of  carbon powder  rather than
                      granules.   Two 6.4 mm water  taps  were  added to facilitate wash-
                      out operations in the feed mechanism.
                                                      40



^•jJy . _ *.-.

-------
Gnat"*'-""-''^-."*"*• T--*!».t-*"•n>ify'^»prtt»~t«ryi^r*]^s*?"*••«»•; «*"•*•••""••• ?«w" •^^•--^^^^'j'»^^tiyji«if^i^ij!* wFvJ;r»yy^"?fsT'?^^3^^?i^f*i^MiJB»^
                       (3)  In the  final portion  of  the kiln  additional tumbling  flights
                            had to  be. added to  get  a  gentler  turning  of  the  carbon  and
                            prevent fragmentation.

             ASSEMBLY

                 With the delivery  of  the trailer,  installation  of  system components  was
             begun.   With  only  minor  changes,  components  were  located as  identified in
             the spatial  arrangement.   All  equipment  mounted  within  the  trailer  was
             bolted  through the floor of the trailer to  the steel cross members.

                 A common  framework was  installed  below the  trailer  bed  to  support  the
             6 pumping units.   Below  deck  supports  were also  installed for the  7 tanks;
             3 for fuel, 2 for caustic and  2 for  water.

                 Lugs were welded  to  the main trailer  beams.  The support  work was bolted
             to the   lugs.   Pumps  were  bolted  to the support  work.   Tanks  were  held in
             place by  steel straps  connected  to the  support work.  Service  piping  was
             interwoven with the  supports  and  passed  through  the  floor to  mate  with the
             appropriate equipment.

                 As the  assembly  work progressed,   certain accessories  were  added where
             a need  was  indicated.   A  slide  control  valve   was  added  to  the  scrubber
             outlet  to  control  the air  from  the blower.   Roof  hatches  were Incorporated
             over the  two  circulating  cooler  fans.  Flexible mountings  and  connections
             were made  at  several points  in  the piping  to minimize shock and  twisting
             stresses.

             ASSEMBLY REVIEW

                 Upon assembly of all components  on the trailer, an  operational  plan was
             prepared and  reviewed  with  the  Technical  Project  officer at  EPA.   This
              included system drawings,  flow sheets, operating  parameters,  and maintenance
             specifications.  The  system was  approved with only a  few minor  changes in
              the arrangement  and  components.   The Project  Officer  requested  a level-
             measuring mechanism with each support jack  and  elapsed  time meters  for the
             kiln and the dlesel  generator  for  proper  maintenance scheduling.

              SYSTEM CHECKOUT

                 Following approval of the  operating plan  by EPA,  a  system  shakedown was
              conducted using  pure carbon  containing only  water.  The  system operated as
              designed with  only   minor  changes  required   in  the   operating   procedures.
              Operating  conditions are given in  Table 13.
                                                     41


-------

                 TABLE 13.  OPERATING CONDITIONS OF SYSTEM
      Condition                                     Description
    Regenerator Temperature                               916°C
    Incinerator Temperature                   .           1010°C
    Carbon Residence Time                            45 minutes
    Carbon Feed rate                                 .150 kg/hr
                                                       (dry generated product)
    Steam Input Rate                                 .156 kg/hr
    Gas Input Rate
      C02 to regenerator                             .142 kg/hr
      N2 to regenerator                              .690 kg/hr
      Air to Incinerator                            1.420 kg/hr
    Water to scrubber                              54.0   kg/hr
   The only  significant  difficulty came from  localized  overheating in the
kiln during  heatup.   The temperature excursions  were not  severe  but they
did trip  automatic shutdown  operators.  This interlock  was  disconnected
while leaving  the  alarms in  place.  Whether  this  interlock should  be  in
place during  system  operation  is  a  decision   which   will  require  some
operating experience.

   The successful  shakedown run was  followed  by regeneration  tests using
contaminated carbon.

   In preparation  for the  system  demonstration, EPA had shipped  to  MSA
drums of  wet  spent  activated  carbon  used  In  the  cleanup  of  a  spill  in
Plains, VA.   A preliminary run had  been  made  with this  carbon  in  the
laboratory-scale regeneration  unit during  the design phase of  the mobile
regeneration unit.
   The pollutant  in  the  carbon  was  primarily Toxaphene  (C^o^ioClg) plus
smaller quantities of other chlorinated compounds such as Aldrin
Dieldrin (C^^ClgO), Heptachlor  (Cio^Cly), and Chlordane (CioH6cl8)
carbon was discolored with a brown material  that appeared as a thin layer on
the outside  surface  of  the  granules.   On  the  basis   of  bulk  density
measurements, the  pollutant content  was about  13% and water  content was
about 52% by weight.   Both percentages  are based  on the dry  weight of the
regenerated product.

   Two runs  were made  In .which  an 88% bulk  volume yield of  reactivated
carbon was attained.  The large loss is believed to be due  to removal of the
brown mater la',  from the  surfaces  of  the granules.   Table 14 presents the
Iodine numbers and bulk densities of the spent and regenerated carbons from
these runs.  The carbon was not identified, but on the basis of density and
Iodine number  appears to  be Pittsburgh type  CAL carbon.  If  this  is the
case, the  carbon was  completely  regenerated.   All  HC1  was  removed in the
scrubber.

-------
                          TABLE 14.  IODINE NUMBERS
                               Iodine No.             Bulk Density
       'Carbon	"" (mg/g)                    (g/cc)
                             Run 1    Run 2
Pittsburg CAL                 960      960            0.500 dry
Spent Carbon                  690      710            0.577 dry, 0.844 wet                  1
Reg. Carbon, Run 1           1030      850            0.507 dry                             •
Reg. Carbon, Run 2            960      940            0.510 dry                             ]
	-  - -                                                        ^
   The success  of  these  tests  demonstrated  the  operating  status  of  the
mobile regeneration unit.  On  February  8,  1979 the unit was picked up  by an
EPA contracted hauler  at  the Evans City plant  of MSA  for  transportation to
the Hazardous Waste  Engineering Research Laboratory  at Edison,  New  Jersey.

   Eight photographs  are  provided to  give  general   views   of  the  mobile               j
regenerator/incinerator.  Figure  4  shows  the  van  closed  for  storage  or
transit.  Figure  5 shows a rear  view of the van open for  operation.   Carbon
is being transferred from a drum into the carbon  feed hopper.   Figure 6 is a
side view of the  carbon feed and  the  kiln  with the incinerator mounted above
it. Figure  7  is  a head end  view  of the kiln  showing  firing  breech  and  gas
burner.  Figure  8 shows the  side  of  the  unit  opposite the  kiln with  the
scrubbing towers  and  water  filtration  units.   Figure  9  shows the tank  and
pump assemblies  slung beneath  the bed  of the  trailer.  Figure 10 is  the
control panel in  the  forward end  of the van  with the  carbon  screening unit
in the  right  foreground.   In  Figure  11 the  van is  shown coupled to a stub
tractor leaving the MSA plant enroute to EPA.
                                      43

-------
  SfcGIN
                                        Figure 4.   Enclosed trailer
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                              Figure 5.  Trailer  open for system operation
     2 3-'8"      w


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                                                                                     TOP ')f
                                                                                  A.  W.E
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                 ; Figure 6.   Profile  of  kiln and incinerator
              " • I
                            Figure 7.  Head  end of kiln
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EPA form r.fjO-4 (t-601
II-KI vio>rjt_v CIN. KPA
                                                       TYPING GUIDE SHEET

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                        Figure 8.  Scrubber and filtration equipment
                       i                     -
                     Figure 9.   Tanks and pumps beneath  trailer bed
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       Li_3:i_i	m
          Form Z.I.'XI-'t M-80i
                                      PAGE (;v-v,ijin
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 BEGIN
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                                                                                       TOP or
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                        Figure 10.  Control panel and product  screener
                                Figure 11.   Trailer In transit
   ~1 3 'p-'
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         EPA Form E3&0-4 (1 BO)

         [PKt;VIOU£L.y CIN. UPA FOHM 247)
                                           PAGE NUMliEH
 i;OTTOM or
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                                                             TYPING GUIDE SHEET
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