Co-principal Investig~tors Robert Pfeffer, Ph.D

EVALUATION AND TEST PROGRAM
OF A 50-TON PER "WASTE CONVERTER"
Investig~tors
Co-principal
Robert Pfeffer, Ph.D, GabrieliTardos, Ph.D
and Alberto LaCava, ~h.D.
for the
United states Department of Energy
Office of Inventors Support Division
under Contract DE-FGOl-82-CE-15126
F. J., Ramos
Technical Director
i
2148 Nw 17th Street
Pompano Beach, FL 33069
Phone' (305) 950-0222
(BOO) 932-9652
Fax
;(305) 960-1050
:;;)
,~,
TABLE OF CONTENTS
ABSTRACT
EXECUTIVE
SECTION A
1.
2.
3.
4.
5.
6.
7.
B.
SECTION B
1.
2.
3.
4.
5.
SECTION C
1.
2.
3.
4.
5.
6.
7.
B.
9.
10.
SECTION D
1.
2.
3.
4.
5.
...........
·.......
SUMMARY • . . . .-. . .
iii
iv
·........................
Introduction • • • • • • • • • • • • • • • •
Background • • • . • . • • • • • • • • • . •
Professional Consultants • • •
• • • • •
Process Description • • • • • • • • • • • • •
Air Pollution Testing • • • • • •
• • • •
Air Emission Standards • • • • • • • • • • •
Dioxin and Furan Emission Standards • • • • •
Universal Emission Standards • • • • • • • •
·.................
• •
• •
• •
• •
. .• .• .• .•
Description of the Facility and Equipment
Measuring Equipment • • • • • • • • • • •
Computerized Data Acquisition System ••
Process Control in the Plant
• • • •
Software Development • • • • • • • • • •
• • • •
• • •
• • •
........
·............
Introduction . • • • . • . . • • • • • . • • . •
Scarifier • • • • • • • • • • •
• • • • • • •
Dryer . . . . . . . .. . . .
. . . . . . .
Char Ram
.
.
•
Stack Damper
Haste Converter
..... • .
• • • • .
• .
• • • • • • • • • • • • • •
............... .
Temperature Monitoring • • • • • • • • • • • • •
Pyro Burner . • . .
Burner History and Re-Design • • • •
• • • •
Conclusions • • • • ••
• • •
0
•
•
•
•
•
•
•
•
•
•
A-4
A-4
A-4
A-5
B-1
B-1
B-2
B-B
B-10
B-12
C-l
C-1
C-1
C-2
C-3
C-3
C-4
C-4
C-5
C-5
C-6
D-l
Introduction
. • • . • • . . • . • • . • . .
D-1
Operational Characteristics of the Plant • • • •
D-1
A SIMULATION MODEL OF THE PLANT • ••
• • •
D-13
MATERIAL AND ENERGY BALANCES AT THE DESIGN
CONDITIONS
• • • • • • • • • • • • • • ',. ~ -. • ..
0-13
MATERIAL AND ENERGY BALANCES UNDER
ENVIRONMENTAL TEST CONDITIONS • • • •
0-14
...
SECTION E · . . . . . . . . . . . . . . . . . . . . . . . .
1.
MUNICIPAL SOLID WASTE AND SOLID RESIDUE.
..
2.
3.
4.
A-I
A-I
A-I
A-I
A-I
STACK EMISSIONS • • ••
•• • • • •
• • • • • • • • • •
EMISSION CONTROL
CONCLUSION • • • • • ••
• •
APPENDIX 1 PLANT SIMULATION RESULTS
TABLE 1 - DESIGN CONDITIONS
TABLE 2 - ENVIRONMENTAL TEST, ACTUAL CONDITIONS
...
E-l
E-l
E-13
E-22
E-25
Numbers
A-1
B-1
B-2
B-3
D-l
D-2
D-3
D-4
D-5
D-6
D-7
D-8
E-1
E-2
E-3
List of Figures
schematic of the Process.
schematic Representation of the waste
Converter unit at Testing site.
Instrumentation and Process Control Diagram.
Schematic of Data Acquisition system.
Flowsheet of the waste Converter Plant.
Effeciency of Volatiles Conversion in the
waste converter. ',,',.' '!", ,
Municipal waste ,Moisture 'Effedt on Theoretical
Energy productionpr~ lb., of wet waste.
Ste~ ;Eriergy VS ,Feeprat;.e Htfficiency Depends
on Feedrate . ' 1 "
,
Total Energy VS Feedr'ate" Efficiency Depends
on Feedrate. ,
Boiler Exbess Air Depended upon Feedrate.
Steam Production"of Moisture'.,
ComparisoI):, Plant Simulation with Actual Results.
Typical Coinpos'itiori, of>~SW.
Volumeariki weight Reduction of MSW.
Hydro,...Sonic Scrubber.
A-3
B-4
B-5
B-9
D-2
D-4
D-6
D-8
D-9
D-ll
D-12
D-15
E-2
E-7
E-24
ltfumber
lB-1
D-1
D-2
))-3
))-4
E-1
E-2
E-3
I~-4
E-5
E-6
E:-7
E:-8
E-9
E:-10
E-11
E-12
E-13
Key to Temperature and Pressure Numbering
System, Figure B-2.
Conversion to Gas.
Conversion to Energy.
Steam Rate VS MSW Feedrate.
Comparison, Simulation VS Measured Emissions.
MSW Proximate Analysis.
MSW Ultimate Analysis.
MSW Hazardous Characteristics Analysis.
Char Proximate Analysis.
Char Ultimate Analysis.
Char Hazardous Characteristics Analysis.
MSW Volume and Weight Reduction.
Heavy Metal Concentration.
Air Pollution Testing Results - Uncontrolled
Emissions.
New Jersey Emission Guidelines for New Resource
Recovery Facilities.
Air Pollution Testing Results, Uncontrolled
Emissions.
Uncontrolled Heavy Metal Emissions.
Comparison of Waste Converter Controlled
Emissions.
B-6
D-3
D-5
D-12
D-14
E-3
E-3
E-4
E-8
E-8
E-9
E-10
E-10
E-14
E-16
E-17
E-20
E-26
ABSTRACT
This overall project was begun in 1978 under the Non-Nuclear
Energy Act of 1974. Under the Act, a request for evaluation of an
energy-related invention, now known as The Waste Converter, was
made to the U.S. Department of Commerce, National Bureau of
Standards (NBS), Office of Energy Related Inventions (OERI). The
National Bureau of Standards/Department of Energy (DOE), Energy
Related Invention Evaluation Program, Undertook the evaluation,. The
operating experience of the OERI shows that of, some 10,000
inventions submitted for evaluation about 2, percent were
recommended to the DOE for support. In 1979, thi,s particular
invention, was recommended by NBS to DOE for support to identify the
precise n'ature of the energy savings to 'be made if the invention
were" utilized., In 1982, the Inventors'Support ,Division of DOE
granted, assist.ance: awa'rd No. DE-FG01-82CE15126' for extensive
testing and evaluation of.
a 50-ton, per 4~Y:,waste,.converter.
t'
,
"
The results of tMfinal: testing' ~nd evaluation set forth
hereinafter indicates that the invention has the ability to provide
substantial energy savings in an environmentally safe manner,
utilizing municipal solid waste as its sole sourCe of fuel. The
technology, ary distillation, should be able t,Q'convert a wide
variety of potentially hazardous waste products into useable energy
without
polluting
the
atmosphere.
These
include garbage,
pharmaceutical waste, printers, inks, paper, plastics, solvents,
agricultural waste and Other organic material.
iii
EXECUTIVE SUMMARY
In the past, energy recovery from municipal solid waste (MSW)
has been viewed as a large-scale enterprise suitable for
application only to large amounts of waste processed per day. The
present study, commenced in 1982 and partially funded by the
Department of Energy Contract No. DEFGOl-82CE15126, reports on the
process evaluation of a patented 50-ton per day modular resource
recovery invention known as a Waste Converter. It has been clearly
demonstrated that the waste converter is a viable commercial means
of disposing of MSW and recovering energy at the same time.
PROFESSIONAL CONSULTANTS
The testing of the waste converter was supervised by
Professors Robert Pfeffer, Gabriel Tardos;and Alberto LaCava, of
the Department of Chemical Engineering, ~he City College of The
City University of New York, who were consultants to the project.
The protocol for the testing of chemical emissions from the waste
converter was formulated in accordance with currently existing
regulations of the U.s. Environmental Prot,ection (NJDEP).
OBJECTIVES
The basic objectives of the project were first set forth by
the U.S. Department of Commerce, National ~ureau of Standards in a
1979 recommendation to the DOE for support of the invention:
(i)
To gather complete cost dflta, efficiency ratings
and other information throuighout a significant test
period.
(ii)
To have such data accepted as authoritative,
generating such data under the guidance of
respected persons in the academic world.
(iii)
Finally, to release this authoritive data to the
public, to accelerate utilization of this process
in designing energy recovery systems."
The scientific and economic objectives of this s·tudy· were to
evaluate the invention's capacity for converting municipal solid
waste into useable energy and also:
(iv)
To obtain a significant reduction in volume and
weight of the MSW 1Ilsed as fuel.
(v)
To obtain a maximum conversion of MSW into energy
with minimum air and water: pollution.
iv
To evaluate the economic potential in marketing the
recovered resources.
(vi)
Upon completion of the evaluation of The Waste Converter the
basic objectives of an environmentally sound waste disposa~ system
and its related resource recovery capabilities were successfully
demonstrated.
WEIGHT AND VOLUME REDUCTION
,
The tested "MSW' consisted' of over 50 percent biomass. When
subjected to .the destructive distillation process, at temperatures
of about 10000F,the biomass is reduced by over 90 percent volume
and by ove,r75 percent in weight.
!'<
CARBON
;ii ,,'
i'i
cltARm:sIbuE
I.
The biontass' is' 'converted in the oxygen-free atmosphere of the
waste ponverter to' gaseous compounds and into a carbon char solid
residue • Th.e:i'pr6cessed ch~:tis free of living organism. Glass,
metal and '~r.tt pre's'enb in the char are sterilized by the heating
process. Due to tl}e chemical reactions taking place during the
destruct~:ve distillation 0:1; MSW, heavy metals -.., such as lead and
other,e,lie~~pt:s .lik~ chlorine' -- have a tendency to be absorbed or
encapsul.J&t:~Ki dQrttalninantsresist leaching when the char is exposed
to waletlti. 'il:[rrh:i,s ••.. f~!~tu:te .' is!:ponsidered' to be a most favorable
envirdIliY!~~~~ilil!:,Cipa~IIa:~t~!r:i,'St~¢ ~.; dhemical analysis of. these residues
detected no il;iben,zpdio:xins' or dibenzofurans.
.
'i
AIR
\1"-',-::I;i':"'I;:,'
I
"i
<
EMlsstONS'
The most significant air emission finding made during the
testing of the waste converter uncontrolled emissions was that llQ
dibenzodioxins or .dibenzofurans were detected during the processing
of unsorted municipal solid waste. The waste converter if equipped
wi th a Hyd~o-Sonic scrubber can be guaranteed to meet or exceed all
existing federal' EPA and state air emission standards.
L
,,
,,
,
I
I!
,
!
RESOURCE RECOVERY POTENTIAL
Steam
•
When the waste converter produced gas was
combusted in a standard water tube boiler, energy recovery in the
form of superheated steam averaged about 2.5 pounds of steam per
pound of MSW processed. This net energy yield resulted after
efficiency losses in the burner and boiler and energy; requirements
to sustain the process were taken into .account. The Energy Tax Act
of 1978 requires that electricity produced by steam generated from
MSW be purchased by Public utility Companies thereby automatically
assuring a market.
v
Ferrous metal • • • After completion of the process, ferrous
metal was found to be relatively clean and unmelted. It is
recommended that ferrous metal be recovered after processing, only
if economically warranted or necessary to meet specific resource
recovery requirements; otherwise it should be magnetically removed
from the waste stream prior to the drying process and deposited in
a landfill. At present there is no market for unclean scrap.
Carbon Char • • • EP toxicity tests performed on the carbon
char residue after reducing the char to ash showed increased
leaching of heavy metals; for example, l'ead by 244 percent. Carbon
use as an absorbent predates Roman civil~zation and can be utilized
in pollution control. Tests of the adsorbent qualities of the
carbon manufactured by the waste convert~r should be undertaken to
determine if this carbon has industria~ application which would
give it a substantial economic value. Oni the other hand, if burned
this char could add 20 percent to the tbtal energy output of the
system.
Glass and Non-Ferrous Metal • • • These materials do not slag
during the heating process in the wast~ converter, however, the
pulverized condition of the glass and the: minute quantities of nonferrous metal found in the residue makes the recovery of the
materials mechanically or economically u:nfeasible.
CONCLUSION
The results of the environmental, energy and resource recovery
studies have clearly demonstrated that a significant reduction in
volume and weight of the MSW used as feedstock is achieved and that
the process produces a significant amount of useful energy.
Conversion of MSW to energy with minimum air, ground and water
pollution should apply to almost any loc.jl.tion where a facility of
this type is contemplated. It must be t,aken into consideration,
however, that there may be unique local ,factors, such as extreme
climatic conditions or lack of energy users that could influence
the economic viability and subsequent ~plementation of similar
projects at certain locations.
vi
"t'<;lt11
':
,,
;
..
••
l
l
.. i
•
i
t
SECTION A
SECTION A
FORWARD
1.
Introduction
The subject of the testing program was a 50-ton per day waste
converter.
This converter produces a volatile gas product
( sui table as a boiler fuel) and carbon char residue via the
destructive distillation of municipal solid waste (MSW). Actual
testing was performed on a demonstration unit located at Marcal
Paper Mills, Inc. in Elmwood Park, New Jersey.
2•
Background
Testing of the waste converter was s~pported in part by the
Department of Energy Contract No. DE-FGOl-82CEI5126, under
which an evaluation of the technology was begun in September 1982.
Initial efforts focussed on specifying and implementing the
complete instrumentation and ~ontrol of t~e system schematically
shown in Figure A-I.
An instrumentation and process control
diagram in presented in Figure B-2 and 'rable B-l.
With this
operating
conditions
and
with
many! different
machinery
modifications in order to optimize the process. Upon completion of
this phase of the program, environmental! testing of the waste
converter was performed by an independent tEi!sting laboratory. This
testing encompassed the sampling of the !( 1) MSW feedstock, (2)
produced volatile gas (fuel), (3) char res~due and (4) stack flue
gases.
u.s.
3.
Professional Consultants
The overall program was supervised by Prof. Robert Pfeffer,
Gabriel Taros and Albert LaCava of the Department of Chemical
Engineering. The City College of the City University of New York,
who were the consultants to the project.
Actual testing of the
environmental discharges was conducted· by Princeton Testing
Laboratory of Princeton, New Jersey, A New Jiersey-approved chemical
testing laboratory.
4.
Process Description
The waste converter is a continuous ~elf-sustaining process
utilizing a combination of patented devices which convert 50-tons
per day of biomass waste into the heat equivalent of about 3,000
gallons of fuel oil in the form of hot' off-gases, which are
partially used to heat the system; the r~maining gas is used as
fuel in a separate steam boiler. The process, Figure A-I, is based
on the principal of destructive or dry distillation and produces a
A-I
volatile gas and carbon residue; no liquid fuel of residue is
generated.
The processed MSW is reduced by about 90 percent in
volume and about 75 percent in weight.
Shredded MSW is fed into a rotary drying unit, which utilizes
process waste heat, to remove excess moisture. After drying, the
MSW is transferred directly into the waste converter using
hydraulic ram. The waste converter unit is an oxygen-free slowly
rotating retort maintained at a tempElrature somewhat above 1000
degrees Fahrenheit. Within the waste converter, the conversion of
organic materials, ~swel1as'thegeneration of gas, takes place.
This gaseous product is then 'c:ombusted in situ in a standard
(Babcock wilcox) water tube steam boiler to produce 225 psi
superheated steam at 435°F.
The "key to this technology is the waste converter. The high
temperature and 'the absence of oxygen in the retort permit no
dire,~t incineration, or b~rning of the MSW to occur.
Furthermore,
t,hese
•
pa~ameters,allow
.for
the
generation
of
volatile
gas that can
'_
,I
"',
'.
be "urt,il,ized ,as ,'a bOl.ler ,fueL
As a result, the waste converter
p.F9dpcersuse,fulenex:;gyfrom muniqipal solid waste, while minimizing
~~e,jI'0Hut~~m, F~rCl~lems,i1orinally associated with mass-burning
l.~c~p,e:r::p.~ors .,
1_
,,',
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,
A-2
----------~~-------------.hi.
-~-------
_. ,~I,__-
·oa __
. • •_
..--
'---~-
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.~~'::':-·"il
.
.;
SCHEMATIC OF PROCESS
BOILER
SHREDDER
0w
.A
~~ J!:}i.'
~
'1m
((\\ MAGNETIC
Yw~
SEPARP..TION
o
"
0,
, ,
1
PRODUCED GAS
r---7
DRYER
...
!to MUNICIPAL SOLID WASTE
,..!---L-,--'
I
w
---<7 ~I"ASTE
CONVERTER
",'
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~~II.
.'
~
~Q~
j
GAS TURBINE
I
•
RAM
1 ,I
.r
I
STEAM, TUR BINE
,',t,
WET REFUSE
,,*ETAL BINI7
'GENERATOR
~
'-',
: PRODUCED
I
GAS
.J.
l
(115 ... useD TO
SUSTAIN PROCeSS)
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C>
C
::rJ
\
CHAR BIN ' /
o
0
m
>I
...
5.
Air Pollution Testing
Environmental testing was -conducted on waste conversion.
Technology's demonstration unit at Elmwood Park, New Jersey. The
tests were performed while using municipal (residential-commercial)
solid waste from the Monmouth County Recl8.lllation Center, Tinton
Falls, New Jersey.
Air pollution stack testing was carried out in accordance with
methods and procedures established by the U.S. Environmental
Protection Agency (EPA) and the New Jersey Department of
Environmental Protection (DEP).
All samples were taken from a
common stack venting the drying unit, distillator unit and the
boiler. This stack had no pollution-'contrpl equipment installed
for the removal of, air contaminants.
.
6.
Air 'Emission Standards
Under current air pollution regulations pertaining to
Prevention of Significant Deterioration (PSD) and Nonattainment
Area New Source Review (NRS), specific numerical emission standards
are not defined for a new source. Each proposed new facility must
propose emission. standards that reflect Best Available Control
Technology (BACT) (for PSD) and/or Lowest Achievable Emission Rate
(for NSR) for the equipment to be installed.
The environmental
regulatory agency: reviews the proposed emission standards and, on
a case-by-case b$.sis, determines whether or not the degree of
control is sufficient to protect human health and the environment.
7.
Dioxin and Fhran Emission Standards
Dioxin and furan emissions from municipal garbage incinerators
have only recently become an issue because only recently has the
technology been developed to measure these emissions in minute
quantities.
Dr. Barry Commoner l , Director of the Center for the Biology
of Natural Systems, Queens College, states that dioxin is a
chemical compound which is created when lignin is burned with
chlorine. The prime contributors of chlorine to household waste
are products mad¢ of polyvinyl chloride while wood and paper are
the principal contributors of lignin.
The debate over dioxin
emissions is complicated by the fact that, as of this data, there
is no univers.ally accepted standard for what), if anything, is a
safe level of exposure.
lThe New York Times, December 5, 1984, Metropolitan Section,
p.3.
A-4
During testing of the waste converter, no dibenzodioxins or
dibenzofurans were detected in t.he stack flue gases emitted from
tbe destructive or dry distillation of municipal solid waste.
S"
Universal Emission standards
It is important to note that at present there are no universal
emission standards specifically defined for new resource-recovery
facilities.
A-S
SECTION B
SECTION B
THE RESEARCH & DEVELOPMENT FACILITY
1.
Description of the Facility and Equipment
The test facility was housed within a 45' x 50' x 36' clear
span steel pre-fabricated building. The building was erected on a
8-inch steel reinforced concrete slab. An overview of the facility
is pictured in Figure B-l. Included in Figure B-1 are Detail I-A
and Details 1 to 9, which correspond to the equipment described
below.
Municipal solid waste (MSW) feed~tock used during the test
period was provided by Monmouth County 'Reclamation Center (MCRe).
all MSW was shredded at MCRC, loaded in a standard 40' transfer
t:railer and then trucked to the test site, a distance of 128 miles
round trip. The shredded MSW was then 'unloaded from the transfer
t:railer to a Keith Walking Floor (Detajil 1): live-bottom storage
container of approximately the same dimension as the transfer
t.railer. The Keith Walking Floor, suppll~ed by Keith Mfg., Co., was
modified with a computerized electronic strain gauge scale system,
(Detail 1A).
The floor allowed the weighing of refuse and
a.utomatically regulated the feed to the waste converter. The Keith
Walking Floor was an ideal metering device in this application.
The test facility was capable of shredding incoming waste to
a uniform size.
The rotary shear-type shredder (Detail 2),
supplied by Eidal International, was fbund to be ideal for this
application. The slow-speed shredder is specifically designed to
reduce dust and eliminate the possibility of explosions that are
associated with hammer mills.
Since its inception in 1972, a
period of some 13 years, there has not been one reported incident
of an explosion involving a rotary shear shredder. The shredder
was located over the Keith Walking Floor. The shredder was fed by
a modified Heil hydraulic lifting system. Objects such as engine
blocks, hot water tanks and tree stumps had to be separated from
the waste stream before shredding.
Experience indicates that a
c.ommercially
available
Grizzly
hydraulic
lifting
device,
manufactured by Crane Equipment Mfg., Inp., should be incorporated
in the system to replace the experimenta~ hydraulic lifting system.
The Scarifier (Detail 3) was design'ed and constructed on site
and was installed at the discharge end 6f the Walking Floor. The
sc::arifier, in conjunction with the computerized Walking Floor,
off loads shredded waste at an automatid,ally pre-set rate ranging
from 10 pounds per minute to 100 pounds!per minute. As the waste
is discharged from the. Wal~ing Floor. pnto a feed conveyor, it
passes through a magnet~c f~eld (Deta~l 4) removing the ferrous
metals. The waste is then transported ~o the rotary dryer.
B-1
The FioKi Dryer (Detail 5) has one major moving component: a
rotating steel tube 35 feet in length, and 6 feet in diameter
enclosed in an insulated steel oven. The dryer is installed above
the distillator. The discharge from the dryer passes directly into
the feed ram of the distillator firebox is used in the drying
process.
The Waste Converter (Detail 6) is similar in design and
construction to the dryer. The major component of the converter is
a, steel retort tube 32 feet in length and 4 feet in diameter. This
tube! is also enclosed in an insulated oven.
As the feed ram
(Detail 7) forces the waste into the retort of the converter, the
waste, is cpmpressed into a semi-solid plug , thereby creating an
air-tight seal. ", After, the ~aste hasbeE!m forced into the retort by
ther atn sY:Ftem, destrut:ti:v~',or dry distillation begins to take
place in ,the ' ox~gen~free ::', atmosphere.'
The waste, continues to
d~compbsea~ itmovesslo..tly through toe rotating retort to the
dlii;t:ha!tge"eridofithe system.
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,
G'a's produced by the ,dry distil1~t:;ionoftH~ organic materials
of the amount , requilied to sust,ain the
converter , i s draWI'loffand is immediately
burne~La~ ':Ii~ue;l'iih 'c;tspecJially' cOlnstruc,ted ' gas" burner (Detail 8).
~his9~S't:'~nilb~' bU'rnedl;hy itself Or fited int:6njunctionwith other
fuels tl:ilInthe': e\rent,lii6'f':~ ,hbiler:p;hu:tti,own oran,overprodu¢tion of
gas, the gas isauto~aticaliy flared.
th~':MSW , i n excess
tempet:atil1~elof,th!e "waste
in
,
~;
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Ylt,:
~.
,:j."
Ii: '_I _
'-',
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...
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~fiteffuost;'9fthei,volati!Le\$>roducts have been extracted from
the b;jliP'IIlf~s'(MpW) , ·thEH remaining\char residue is removed from the
wastei\l~qpy~:ttJrl~yi'ia, hYdfau.tililici:::ra:m (,Detail 9).; At this point, the
drigil:l!elil,' ,)jlL~m~~i,? :i,('HSr/F t&at :llwa:sl$ubjected to the dry distillation
proc~~!~ ~a!~ilpeeni'l~etlu~~dlllinil:,'8~).l«l~lbyover 90 percent and in weight
by ,ovW4'ltt",15111:[perfl¢n,lt,+'i'lli-rhelii:rtel~!f~e~~ei:~,ime in the waste conve.rter is
cib, o~t,ljl,lliW'5,' , ,'~,ti,'n, u,::~~,'I, ~'":i,!i~ndi!',I !ie" ,'X!,!I.I~, ,Q, ,',:, I:i, I~, i,'.~, :I"l i,',i.rt,L,~'e, '~S.W,' and ~esul tant, resl.due. to
tefll',pe,:',ti!!~,!t,,ultil,, ~~',', JJ,bi!"I~:lI!, ll±e,S$r',:dO,',:,f,' lH10,'O"IO,f,)EI,irll\',i",' , T;Hl., s extended exposure, to hl.gh
tempe~~lt:iiu:llt:el~i' [;nllil~d, ox'YJIS'~n':'lfF~el!lfa~m.oSlphere, converts the volatiles
qf. i1i~~!iI'i~ "~~S~i!ll!fidll!!FJii$!i 1~~(fii!~~~:il'~l~ a:id~esidue of char. The char is
freellll#>iif 'II,
in(iilIIP~~~~f~I#~ .1:II!ii~~~I,4:):,S 1!!Ii~ound in the residue such as
gliassWII!I~~,'i!~~~li!ijriiJ#I!~ea~~th!li~,~erril:ized in the heating process •
. '
2:.;
,'t,l1!li!j!i:,. ,. ': :::-:: ,: ~i [l~; \ ,: '::' I:,.,
;1 ~~a!s;uri:ngJ",flq1!ilji:iPmerit::
';: !11i!~'i '.I!li::! (::ili:l; ,_
1
i,
'Ii!
The instrumentation and process control of the 50-ton per day
waste converter was carefully designed and installed during the
test period. AS:chematic diagram of the plant showing the location
of the,. thermocouples, presshre transducers, pitot tubes, orifice
meters,!, dampers lanit p~elltnat:i:c actuators is given in Figure B-2 and
Table:!a-l.
'Theinstrl.'hnent.ation and control of the boiler was
instaiJ;iledisepara!~efY tiy :ltheCleaverBro~ks Corporation. A total of
35 CntIOmeI"'Al.ume~\EhermcilcolipleS t 19 Vall.dyne pressure transducers,
15 ori.fice p]:at·es and 3 pitot tubes were installed and connected to
a Burr Brown industrial-type front end computer interface which was
B-2
located near the operator control panel of the plant. The Foxboro
actuators were pneumatically operated and had the capability, by
using current to pressure transmitters, to be computer controlled.
B-3
FIGURE;
ELECTRH
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KEITH WALKING FLOOR
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SCHEMATIC REPRESENTATIONS OF THE
CONVERTER UNIT AT TESTING SITE
W~STE
B-4
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PNEUMATIC
ACTUATOR
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INSTRUMENT ATION AND PROCESS
CONTROL DIAGRAM
O~"PER
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SENSOR (LOAD CElLI
STREAM HUMBER'
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TABLE B-1
KEY TO TEMPERATURE AND PRESSURE NUMBERING SYSTEM
TEMPERATURES
Pyro Gas feed line into boiler
Gases exiting retort fire box
Gases exiting dryer
Dryer bypass duct
Gases from inside dryer
Gases from dryer fire box
Boiler exhaust
Flarestack temperature located above the roof
Steam from boiler
Flarestack located below roof level
Converter retort tube interior temperature
Converter tube skin temperature
Tempei'ature of material feeding into dryer
Convei'ter fire box temperatures
PRESSURE TRANSDUCER
P I 'O-P 14
PIS
P 16
P 17 -P 24
" P 28
P 33
PI
P2
P3
P 26
P 2S
P 27
Gases entering dryer, orifice plate pressure drop
Drrer bypass, orifice plate
Gases from dryer interior, orifice plate flowmeter
Gases exiting dryer, orifice plate flowmeters
Boiler s.teampressure
Natural 'gas flowmet.er, orifice plate
A:j;,r intake, flow topyro gas burner in retort fire box,
pitot tube
pyro gas flow into retort fire box, pitot tube
aq~ler pyre!> gas flow, pitot tube
Boiler exhaust gasiflow, pitot tube
Dryer exha~s~ gases and bypass gases, pitot tube
Flifirestack, [located! above the roofline, pitot tube
B-6
The Burr Brown front end computer communicated with a LabTech
70, microcomputer (Laboratory Technologies Inc.) which was
installed in an elevated trailer that overlooked the plant. This
trailer served as a combination of instrument and control room and
office for the personnel involved in the testing project.
The LabTech computer has 380Kbytes of memory, a 10 MB
Winchester hard disc, a floppy disc. back-up and the necessary
software for Real Time Multi-tasking operation (IRMX - 86 operating
system).
The computer was also equipped with an AIDS Viewpoint
terminal, an Epson MX-80 dot-matrix pdjnter and a Hayes smart modem
to allow telephone communication to and from another computer or
terminal.
The entire computer syst~m as described above was
carefully selected by the consultants iat the time as the best and
most cost-effective system available to handle the multi-tasking
required to properly evaluate and control the operation of the
plant.
'
In addition to the computer systiem, a number of analytical
instruments were installed for analyzinig the produced gas and stack
gases.
A 1/2" line from the stack to the instrument room was
installed. This line was heated usingl an electric strip to 150°C
and was insulated to pH·Tent condens~tion of HCL using an HCL
analyzer, and for partie" lates, aftejr cooling and removing of
water, by using a ,<oyco l<:·del 2~7 co~nter. The cooled stack gas
could also be aL; lyzed ,ising gas !chromatographs which were
specifically purchased for this task.
One of the chromatographs
was a GC-Orsat analyzer and was used for measuring N2 , H2 , CO, and
CH 4 ; the other was a hydrocarbon ahalyzer and was used for
hydrocarbons up to C70 • The measurement of S02 and NOx was to be
performed by an outs~de laboratory.
The gas produced by the dry distillation process could be
analyzed by first separating out any co~densible liquid using a dry
ice trap and then sending the non-bondensible gas to a gas
chromatograph. The liquid condensed in. the dry ice trap could then
be recovered with a sol vent and analyz'ed by chemical means. The
combination of the gas and liquid anal~sis could then be used to
assess the composition and heat content ,of the gas and vapors which
are produced by the waste converter before it was sent to the
boiler.
This information, together with the rate of flow of
produced gas, was used to determine the efficiency of the process.
The amount of feedstock at a per-mlnute rate of processing by
1:he waste converter was digitally displaiyed automatically using the
LabTech 70 Computer. The Walking Flooriwhich discharges the waste
onto the feed conveyor was equipped with four load cells.
These
load cells are connected to an amplifi~r, transducer and then to
,
B-7
the digital readout. The signal from the load cells was also sent
directly to the Burr Brown front end and continuously transmitted
to the LabTech 70 Computer.
The installation of the aforementioned equipment and
measurement devices involved many hours of skilled labor. Much of
this equipment was installed after the system had been constructed
and was operational. Portions ·of the converter's duct work had to
be dismantled, re-designedand re,...assetnbled in order to accommodate
tJbiei,on-goinginstallation of ,the measurement equipment. The,retrofitting and" field "install'ation, 9f this equipment resulted in
educatingbothen~in~~rs; an~ :te,s:ting ,personnel. in the practical
dperation'iofthe tel?t': ,f~qiHty.
3,!'comp~~erized'Data Aci~U:isi.t:.iohsyst':,em
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The data acquisition and control of the plant was also based
upon the LabTech70 measurement and control computer a.nd a Burr
Brown MCS100A-116 'data acquisit;ion. and control front end.
The
sensor~J f;,~ansd/.1cers ,'and a!?:tuator~ of the Waste ,Converter Plant are
shoWDi:i.'n :F~9ure:~,-3.!'
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The installation of the instrumentation and sensors was
described in Section B, "Measuring Equipment." An overview of the
position of the sensors in the plant is given in Figure B-2 and
Table B-1.
After installation of the measuring devices, an important task
was the calibration of the sensors. This was performed for all
thermocouples, pressure transducers and load cells in the plant.
The calibration data was incorporated into calibration subprograms
resident in the LabTech 70 Computer.
Some of the sensors were
recalibrated frequently (load cells and pressure transducers ) since
they exhibit zero drift and some variation in the calibration
constants. All calibration programs were written in FORTRAN, to
provide automatic conversion of the signals received by the front
end compu,!::erinto the desired engineering units.
Further
description of the data: acqui~ition software is given in the
section "Software Development~" Data obtained.du!I."ing experimental
runs of thewasteconV'eiter plant were printed and a backup of the
data was sayed on floppy diskettes.
4.
I
I
I
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~
Proces!S Contro.l in the Plant
Data obtained during the preliminary testing period suggested
that the following factors were important in regulating the overall
effectiveness of the waste converter plant:
I.
Pressure Control in the Waste Converter: The pressure in
the waste converter had to be maintained very close to atmospheric
pressure, and slightly positive •. This prevented entry of air into
the retort chamber.
Pressure fluctuations were monitored and
controlled to insure smooth operation of the boiler burning system.
To attain control Objective 1, the pressure was measured with
a t:r:ansducer ,.PT3 , (see Figure B-2) and the barometric damper on
stream 27 (same figure) was opened or closed to allow for pressure
equalization. In the case of excess pressure, the damper opened :to
allow some of the fuel gas to flare in the main stack, thereby
equalizing the pressure.
The control loop was implemented in a program that operated on
a one-second cycle, using a PID (Proportional Integral Derivative)
numerical algorithm. However, since the barometric damper presents
a highly non-linear response to output position, an adaptive
control algorithm was implemented, which was able to correct for
the nonlinearities of the device. As a result the gain of the PID
controller was modified as a function of the valve opening, in that
the response of the feedback loop was always tuned according to the
Ziegler-Nichols criteria. The control loop had a manual override,
in case of equipmeIlt failure.
B-IO
-'}'~>f~;';~*~~~'~t{;-~;$i~t;{~J~~_ ~i~i~10;rf-"'4\1:},!/~j~<\~~~~~'~k'i ~:i>::J
II. Moisture Control of the Feedstock: The waste converter
plant uses waste heat to' eliminate moisture present in the
municipal waste.
The transfer -of heat and the subsequent
vaporization of the moisture takes place in the dryer. The control
objectives for maximum effectiveness of operation of the overall
plant are to permit the maximum transfer of waste heat so that the
municipal waste is as dry as possible. The amount of heat being
transferred has to be controlled.
Control Objective II was implemented insuring that the
temperature sensed by thermocouple T16 was always lower than the
ignition temperature of waste.
When. that pre-set value was
reached, pneumatic actuators closed the dampers in streams 10, 11,
12, 13 and 14 (preventing the admission of hot waste gas to the
dryer) and opening the damper on stream 15, to bypass the hot gases
directly to the main stack A proportiona~ controller algorithm was
used in this loop, with a scanning frequency of fifteen seconds.
III. Feedrate Control:
The feedrate should be fairly
cClnstant.
This improves operation of' the solids manipulation
equipment such as the dryer and the ram ihjectors. This results in
minimizing swings in the produced gas flQ~ rate. The efficiency of
the magnetic metal separator unit is also improved, and in turn
reduced possible blockage in the solids handling equipment.
Control Objective III was implemented from a calculated value
of the feedrate, received from the walking floor load cells and
cClrrected by calibration.
The algorithm controlled the average
feedrate by modifying the Keith Walking Floor hydraulic movement.
This control system was based upon a reading cycle of one second
averaged through fifteen seconds, to avoid excessive fluctuation of
the controls of the walking floor.
IV. Temperature Control of the Retort: The optimal operating
temperature of the retort has two considerations. On one hand,
extremely high temperatures shorten the life of the retort tube and
enables the melting of glass, thereby creating slag. On the other
hand, it is desirable to operate at a temperature as high as
po>ssible, to increase the yield of volatile gases from the
feedstock.
An optimal temperature is maintained to serve both
considerations so that plant efficiency is Jr,aximized. Once this
temperature is established, the objective of the control system is
to maintain this pre-set value.
Control Objective IV was implemented by using the signal from
thermocouples T35A and T34 and a pneumatic actuator installed on
Stream 1. The actuator modifies the flow of air admitted to the
converter heating furnace. The design of the pyro burner was based
upon a Venturi feeding of the fuel gas driven by the air flow and
B-ll
pressure, the actuator on Stream 1 controlled the flow of fuel gas
to the combustion chamber.
A proportional integral numerical
algorithm was used in this control loop, on a scanning cycle of
fifteen seconds •
5.
.
Software Development
During the testing program, a variety of computer programs and
subroutines necessary for data acquisition and control of the waste
converter plant were written. These routines were integrated into
a final data acquisition and dontrol program, structured ill the
.. following manner:
PROGRAM NAME
FUNCTION
MAIN
Initialization creation of all tasks and
assignment of priorities.
TASK 1
Schedules and keeps the timing of "TASK
4."
TASK 2
Schedules and keeps the timing of "TASK
5. "
TASK 3
Schedules and deeps the timing of "TASK
6. "
TASK 4
1 Sec. cycle fast task. Controls retort
pressure, measures weight and feedrate,
measures steam flow and production,
measures natural gas flow and amount
used.
TASK 5
15 Sec. medium speed task. Performs data
acquisition over all sensors. Controls
retort temperature, dryer temperature and
municipal waste feedrate. Performs units
conversion using calibration subroutines.
TASK 6
10 Min. printing and reporting task.
This task organizes and prints a reports
on the status of the plant. The report
gives the values measured in the plant to
the terminal and printer. Also saves a
data
acquisition
file
on
floppy
diskettes.
B-12
The above tasks use a series
subroutines that were prepared
to communicate with the Burr Brown front end. A description of the
routines follow:
a.
Program Name:
TASK 5
This program is the foundation for the complete data analysis
and control system used at the test facility. In conjunction with
the sub-programs to be described below, "Task 5" communicates with
the Burr Brown front end computer, giving the commands for the Burr
Brown to read the output of the entire network of instrumentation.
It then. reads these values into the LabTech 70 memory, converting
the machine code into appropriate scientific units (degrees
fahrenheit, millivolts, etc.) and makes them available either as a
printed hard copy of as terminal screen output.
b.
Program Sub-routine:
Communic'ate
This sub-routine handles the entire communication task between
the LabTech 70 main computer and the Burr Brown front end. The
main program calls "Communicate" giving j,t a character string line
that represents the command for the fro~t end computer. Through
the ; sub-routines that follow, "Communicate" identifies the
communication port, sends the command anp receives the reply; the
reply being either data or a command ;ceceived confirmation. This
reply is then returned to the main program.
c.
Program Sub-routine:
SPWRIT
"SPWRIT" is called by "Communicate," given the communication
port identification code and the command which is now in integer
fo.rm.
It reads the status of the port and sends the command
integer when the port status is ready.
See program listing
comments for details.
d.
Program Sub-routine:
SPREAD
"SPREAD" is called by "Communicate" and given a port
identification number.
It reads the data in the port after
checking for a "port ready" status. See program listing comments
for details.
e.
Program Sub-routine:
SPINIT
"SPINIT"
initiates
the
communication
port
for
data
transmission as described in the comments on the program itself"
See program listing comments for details.
B-13
f.
Program Sub-routine:
SETBAUD
"SETBAUD" is called by the main program at start-up, to define
the communication rate between the LabTech 70 and the Burr Brown
front end. See program listing comments for details.
g.
Program Sub-routine: HEXA-CONV
"HEXA-CONV" is called by the main program when a hexadecimal
string must be converted into decimal values.
It reads each
loc,ation in the string, identifying- it as one of the hexadecimal
characters with ,values of ,0 to 15 in decimal. The decimal value is
assigned to a variable lid" which then.multiplies the appropriate
power of 16 represented by the location within the string of the
original hexadecimal, character. This value is added to the decimal
base conversion of the'original hexadecimal string.
These subroutines were, complemented by calibration routines
which implement the calibration curves "and equations to calculate
flowrates from pressure drops in orifice plates andpitot tubes.
"
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11
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B-14
•
SECTION C
SECTION C
RESEARCH & DEVELOPMENT ACHIEVEMENTS
1.
Introduction
The R&D facility occupied 2,250 square feet and was design
rated to process 50 TPD of "as received " MSWi the daily disposal
rate required to service a population of about 25,000. In order to
achieve the design feedrate, the following modifications were made.
2.
Scarifier
Monmouth County Reclamation Center (MCRC) was contracted with
to provide feedstock for the test. All MSW, shredded at the MCRC,
was loaded in a standard 40' transfer trailer and then trucked
approximately 62 miles to the test site. At the test site the
transfer trailer was positioned in front of a Keith Walking Floor
storage container which was approximately the same dimension and
elevation as the transfer trailer. The MSW was then pushed into
the storage container via a hydraulic ram located within the
transfer trailer. The MSW loading at Monmouth and the unloading at
the site resulted in over compacting the feedstock.
This
compaction made it virtually impossible to meter the desired amount
of feedstock onto the feed conveyor. Magnetically separating the
ferrous metal from the overly compacted waste was found to be
difficult and resulted in extracting an unacceptable amount of
biomass from the waste stream.
modification/design
:I
The scarifier, a device designed to evenly meter feedstock
flow, was developed after several unsuccessful attempts. The final
design of the scarifier was the product of on-site design testing
and refinement, and in its present form can handle all types of
waste up to any degree of compaction presented by handling. The
device consists of two (2) 8 foot parallel shafts, an upper shaft
mounted above the storage container at the discharge end and a
lower shaft mounted over the feed conveyor. Each shaft has five
sprockets driving five chains on which sickle blades are staggered
along the face of each chain.
The chains have the ability to
rotate in either a clockwise or counter clockwise direction,
thereby avoiding jams. By controlling the number of revolutions
and direction of the scarifier in conjunction with the speed and
direction of the live-bottom storage container, feed material can
effectively be discharged from the container to the feed conveyor
at an automatically pre-determined rate.
C-l
3.
Dryer
Dryer Retort Feed and Seal
The dryer has one major moving component: a steel retort tube
35 feet in length and 6 feet in diameter. As manufactured the dust
seal at the feed end of the dryer retort was obtained by using a
stationary flat plate open at the center, to allow wet feedstock to
inter the dryer. As the tube rotated, ,the contact surface between
"the plate and tube face was greased thereby creating a seal. With
continued use of the dryer, sand, ,glass and other abrasive
llIlaterials worked their way between the tube face and the plate.
~rhe integrity of the seal continually deteriorated and dry material
sifted through the seal.
As this material passed through the
grease seal, drag increased on the rotating tube and caused the
t.ube to stall.
Modification/design
The dryer feed end seal was re,designed during the test
program. The stationary plate was welded along the circumference
of the dryer tube, making the tube and! plate one rotating piece.
Thin a 36-inch circular opening was cut !in the center of the plate.
A feed chute was then manufactured to ftt the circular opening. A
t:ough rubberized canvas seal was mount.ed in the clearance space
between the feed chute and the rotating plate.
By reducing the
"contact area of the seal and eliminating the grease seal, the drag
em the dryer tube was sUbstantially red~ced. The new seal was now
located at the outside circumference of,the dryer tube; therefore,
dry material could not sift through the! seal.
Dryer Flights
The dryer utilizes the waste heat from the converter firebox
to eliminate unwanted moisture in the feedstock. The flue gas from
the converter firebox heats the dryer oven.
The heat is then
transferred from the tube to the feedstock by surface contact.
Initially biomass is never directly exposed to the hot exhaust
gases. During the test period it was observed that the biomass had
a tendency to slide along the bottom of the tube and not tumble.
In some instances roping of the material occurred. Biomass that
was in contact with the skin of the tube was found to be dry but
dense chunks of material had moisture-laden centers that were
thermally insulated by a dry biomass layer.
Modification/design
Three sets of lifting flights were installed inside the dryer
tube.
The first set was comprised of, six 90° flights.
These
f.lights were welded in a staggered manne',r throughout the first 1/3
of the tube at the feed end. The second set was comprised of six
135° flights.
These flights were locat:ed at the midway point of
C-2
the tube. The third set was comprised of six 180° flights. These
flights were mounted in the last 1/3 of the tube at the discharge
end.
As the dryer tube rotated the flights would now lift and
break up the biomass as it tumbled inside the tube. In addition to
the installation of the lifting flights, exhaust waste heat at
200 0 P from the waste converter firebox was introduced into the
center of the dryer tube from the discharge end.
These
modlfications resulted in reducing the molsture level of the
feedstock to an accepta;ble level.
4.
Char Ram
Initially the char residue, dropped through a sealed
transition hopper to a sealed auger conveyor.
This auger then
conveyed the hot residue to . storage bins for eventual disposal.
The auger conveyor presented problems during long-term operation of
the wasteconverte.r. Continuous operation of the auger created a
poor seal ~t the discharge end of the retort tube. This allowed
air to leak into the retort causil).g incineration of the char.
Furthermore th~:'~ugercontin~aHy jammed as a result of .small metal
Objects (can .topS! , I:Ipril),gs, nails,bol t,s); contained. in the ,residue.
1
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To all1evia,te these problems, a hydraulic ram was fitted to the
discharge transitiol). piece. The transition piece became the char
hopper fO~I;t,hellrl~'~. ,The ram was designed to maintain a continuous
materj,;al~~al~I~!thechar was rainmed out to the conveying system
for dtisp~I~~l,r Ihl';l'lte ,ream . syst~m greatly reduced jainS due to the
presence ot l.nerts,l.n:the char.
5.
Stack Damper
The stack damper is installed at the top of the discharge end
of the converter retort.
This damper controls the flow of
aspiration stages.
The first is located several feet above the
damper. This allows for instant combustion of the produced gas as
it leaves the waste converter. Initially the carbon steel damper
was barometric and was assisted by a counter-weighed arm.
The
operator could also manually initiate various damper positions in
accordance with .gas production •
. Modification/design
It was determined that the stack damper had to be redesigned
to operate automatically.
The new damper was fabricated from
stainless steel plate swinging on heavy duty cast iron external
bearings I allowing free operation at high temperatures. The damper
was actuated pneumatically by a signal from the computer which
calculated damper settings in accordance with gas production.
Manual control (as an emergency override) was also maintained.
C-3
6.
Waste Convert.er
Although the waste converter had an operating history, its
opt.imum performance and efficiency was generally unknown. As data
became available from the test program, it was soon apparent that
the waste converter's performance could be enhanced by implementing
design changes. Although the waste converter's retort tube had
been previously used for five years, the other materials used in
its manufacture were new. The purpose in; utilizing the used tube
was to further test its useful life. Certain modifications were
made for the purpose of being able to iattain an additional 24
months of continuous operation for the test project. Creating a
good air seal arrangement on both ends of the retort was of prime
importance.
'
Modification/design
The feedram seal was modified to eliminate air contamination
of the retort atmosphere and to reduce th~ diameter of the seal to
eliminate fines from sifting through th~ seal.
The new design
incorporated a 25" bronze spring loaded radial seal. The original
seal was approximately 44" diameter carbon steel. The modification
prc)ved to be superior.
The discharge seal arrangement was modified to incorporate a
floating bronze ring. In addition to the ring, sealing surfaces
were machined to obtained true and concentric riding surfaces.
Three feet of char flights were removed from the discharge end
of the retort to minimize char turbulence'. Advancing spirals were
installed at the feed end to propel incbming feedstock down the
tube to reduce the back-washing effect of residue to the feed end
seal.
The drive assembly was modified to float with retort
expansion. A torque bar was installed to minimize drive assembly
vibration.
7.
Temperature Monitoring
Prior to the testing program the only temperatures that were
monitored in the system were the firebox temperatures of the
converter. These readings proved to be inadequate for measuring
the actual temperature fluctuations of the interior retort
atmosphere.
Modification/design
It was decided that a prima.ry sensor system was required to
monitor the actual skin temperature of the tube. It consists of
C-4
thermocouples mounted on the skin of the tube and two copper
commutator rings mounted on the tube where the tube protruded from
the firebox housing.
As the tube and the rings rotate,
thermocouple signals are picked up by a brush which rides the
copper commutator ring.
The skin temperature is read at three
points on the tube: feed end, middle and discharge end.
8.
Pyro Burner
The pyre' burner provides the primary heat source for the
distillation process.
The pyro burner is self sustaining and
utilizes gas produced by the' on"going process.
The burner is
located within the firebox of the waste converter. The burner was
found to provide inadequate heat and had'to be re-designed during
the tests •
The. majorproblelq with the burner was uneven heat
distribution 00 the retort tube surface .and failure of its carbon
steel ?omponents t.o withstand the high temperatures ,associated with
increased·
feed; rat:~'s.,
.. .
,.
, .
After approximately 12 months the original pyro burner was
completely scrapped in favor of a more efficient heat resistant
stainless steel. Qurner.
This replacement burner was of a new
design and solvedbrlanyof the problems that were attributed to the
failutet>f th~or!i!~ibal burner. The net result of this redesign
.wastheburne!r:~sabilityto distribute heat where required and
thereby iricreas'e: tli!le feed rate of the waste converter.
,
9.
:
.,
Bur~er·
,
J
-'j;,"
H!iJstdt¥, and Re-Design
In the month of ,F.ebruary, 1983, attempts were made to operate
the commercial gas burner system installed on ;the steam boiler.
The packaged instrumentation system absolutely did not work in
conjunction with the'burner. Malfunctions of this system caused:
:1
1
1
1
Unpredicted shutdowns
EXplosions
Flame outs
Pulsating over pressures
Smoke
Noxious odors
Fire in the main gas line, and a reversal of air flow which
almost caused a meltdown of the main stack.
During the period from May, 1983, to August, 1983, numerous tests
were made on the equipment as designed by the manufacturer and
installed in accordance with specifications.
One of the tests
conducted was a combustion air flow test which proved the system
would never work as designed. This test indicated that as greater
volumes of combustion air were introduced into the burner chamber
by the boiler forced draft fan, the air flow into the boiler
C-5
"
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,'' ' '-":; ;')~;,~~~:~~;:'~;,<,::~I~;i~J <It'_ ' ':1i::' ~;':,l\'~"i' 1
a.ctually reversed at a certain point and blew combustion air into
the gasifier chamber of the retort.
An error in basic
instrumentation logic was discovered and was of such a magnitude
that it precluded .the system from ever operating.
Coupled with
major mechanical design problems, which were discovered in the
burner head, the decision was made to replace the faulty burner
with an in-house burner operated properly. This problem delayed
the overall project for considerable months before it was solved.
10.
Conclusions
As the project commenced the testing group relied upon initial
surveys of equipment suppliers and manufactures which had indicated
that "off the shelf" technology and equipment was readily
available, to support the waste converter plant design. As the R
& D advanced, it was soon apparent that because of the resultant
produced gas and char, unique solutions were required. Therefore,
costly modification or redesign of much of the "off the shelf"
equipment supplied to the project had tp be made to meet project
requirements.
The non-homogeneous nature of the MSW and its
deleterious effect on material handling ~nd flow control equipment
WE!re typical of the factors that nece'ssitated the redesign or
modification of much of the initial equipment supplied to support
the system.
C-6
•
SECTION D
SECTION D
EXPERIMENTAL RESULTS AND DISCUSSION
1.
Introduction
A complete material and energy balance made on the plant will
be presented in this section.
The experimental information
recorded was obtained from runs beginning in December 1982 through
Noyember 7, 1984.
On the last runs, a complete analysis of
particulate and chemical emissions was performed under a joint
effort between Princeton Testing Laboratory and the research team.
The complete results of the analytical study and its environmental
importance is set forth later in this report (See Appendix 2). The
experimental runs were performed using Monmouth County (NJ)
municipal solid waste. A complete elemental analysis of the waste
is also presented in Appendix 2. Figure D-1 shows a flowsheet of
the plant. The numbering, as it appears in Figure D-1 will be used
in the following discussion to identify the flow of overall mass,
components and energy in each of the streams.
2.
Operational Characteristics of the
~lant
The thermal decomposition of waste (dry distillation) in the
absence of air can yield considerable amounts of gases.
These
gases, in the present process, are burneq immediately in a boiler
to produce steam.
At present the waste converter's design
temperature is below 1200 o F. As a consequence, there will be some
small amount of volatile matter remainidg in the waste. A good
measure of the maximum conversion of volatiles in the waste is
giyen by the ASTM "proximate" analysis method. This method uses a
very high temperature to thermally deqompose the waste in an
oxygen-free atmosphere. Conversion of vo~atiles, at the plant will
be lower than the total "volatile contenjt" of the ASTM proximate
analysis. The maximum yield of volatiles is dependent on ideal
reaction conditions in the retort and thJ nature of the municipal
waste that is being processed.
D-1
~'""',2';";' ·-;;:~7,;r.:".'..;;,.=;_~: __ ~;;;.~.::..;~. '.:r::;;;::~5::h:;Tft~::t~,:-.,'-;~,~~:J~.
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:;;;:;;;;+
.._.........-..
& .. _ ..... _ ..._._-_ ...•......
FLOW SHEET OF THE
WASTE CONVERTER PLANT
TO CLEAN UP
AIR FOR FLARE
"')
__
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R
S17
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.
IV
DRIED
WASTE
E
ci
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B
S1
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--~OC-------
MUNICIPAL
WASTE
84
PRODUCEO
S7
GAS_._~
~ S5
S6
G
NATURAL
WASTE
GAS
S.l.~ CONVERTERtl...
l
S 11
M
FURNACE
Kl S9
L
CHAR
AIR
S13
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J
(START-UP]
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BOILER EXHAUST
BYPASS STREAM
TO FLARE
(EMERGENCIES)
DRYER
STEAM
tJ
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AIR FOR
COMBUSTION
o
IH~T
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s 12
WATER
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I
A series of test runs were performed to determine the effect
of different operating conditions on the conversion of municipal
waste to volatile gases.
The runs involved varying the waste
converter tube temperature and the feedrate of waste being put
-through the reactor.
The direct effect of waste converter
temperature is shown in Figure D-2. The conversion is referred to
1the volatile content of the ASTM proximate analysis. The results
indicate a linear dependency of the conversion with temperature in
the range of interest (1000° to 1200° F)'. The varied feedrates did
not significantly affect the conversion during the tests. At the
retort design temperature of 1150 0 F, th~ conversion is more than 90
percent of the total amount of volatil~s available that could be
obtained from the waste.
Under ideal: conditions this is a very
acceptable result for an industrial un~t.
a.
Conversion of Chemical Elements Present in the Waste
,
The chemical elements present .t,n the waste did convert
following different selectivities. ThiJs means that some elements
c:onverted to volatiles in a higher degree than others.
The
c:onversion of these elements in the' plant was calculated by
performing an atomic balance on the "as~ received" municipal waste
a.nd then on the residue char. This bala~ce was performed utilizing
several samples of char exiting the distlillator at 11500 F. Typical
results are presented in Table D-1.
TABLE D-l
COMPONENT
Carbon
Sulphur
Chlorine
Hydrogen
Oxygen
Nitrogen
% CONVERSION TO GAS
71.8
69.6
13.0
97.9
100.0
70.6
STANDARD DEVIATION%
9.5
6.5
9.4
0.5
0.0
9.8
In Table D-1, the relatively high standard deviation is due to
the heterogeneous nature of the municipal waste.
Oxygen is
completely converted at 1150 0 F and is accomplished within the given
residence time that the waste is in the converter. Hydrogen is
almost totally converted to volatiles.
Nitrogen, carbon and
sulphur convert to gases in about equal levels and average close to
70 percent; the remainder of these elements are found in the char.
Only a small fraction of the chlorine is converted to gas, most of
this element was found to be encapsulated in the carbon structure
of the char residue.
D-3
100
EFFICENCY OF VOLATILES CONVERSION IN
THE WASTE CONVERTER
?f.
z
0
95
c J)'
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en
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90
UJ
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0
>
35
.:
00
tOoo
1050
1100
TEST RESULTS
1150
"
1200
C)
C
:0
CONVERTOR TEMPERATURE DEG. F
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. .• --'~ ....... -.",~.~O:'.;.."".~...~~.+i~..:...:,.!,,~.}r':.,'(.r~~...... '"
,
.. .•..:
~
................,'\.~\.;,~~-
b.
Conversion of the Energy in the Waste
The amount of combustion energy or the heat of combustion
contained in the "as received" waste that is transferred to the
m.anufactured gas during the dry distillation process can be
calculated by performing a complete hea~ of combustion balance of
all the various streams entering and exiting the waste converter.
This calculation was performed using samples exiting the waste
converter at 11500 F which gave the result listed in Table D-2:
TABLE D-2
STANDARD DEVIATION
5.5%
ENERGY, GAS
83.68%
c.
Effect of Moisture on the Plant Operation
The detrimental effect of moisture contained in the "as
received" MSW was noticed early in the development of this project.
It was determined that energy production of the plant dropped on
days when the MSW was very wet. On occasion, in the Fall, waste
could contain in excess of 50 percent moisture limiting energy
production.
The effects of moisture can be discqssed theoretically in ;the
plot shown in Figure D-3. The theoretical energy ;available from
1 pound of waste has been plotted vs. the moisture content of the
waste.
The net energy produced is obtained by calculating the
energy released when 1 pound of wet wa~te is processed and then
deducting the total energy required to ~oth heat and vaporize the
water content and to gasify the waste. '. Figure D-3 clearly shows
that as moisture content goes up, net en~rgy drops and at about 75
percent moisture, the total energy relea~ed from the waste balances
the total energy required for gasificati~m and water vaporization.
At this point the plant produces zero net energy.
In actual
practice the limit of operability of the plant is lower than 75
percent. This is due to the energy overhead of the plant, that is
tl:> say, the amount of energy required toi keep the plant running at
its required operating temperatures; thiis also includes the heat
It:>sses of the system.
.
D-5
t".
''?
.ilf;;,:-J:~;
. ~,:;."" --
.-:~:::2~':;:.""-; ~[~::,'U ~-;Z~"",~~l:~-,~2~-- -----=-c=-:::,~,,-_:_:_~
I_._
............ .J't:.
..
........ - ... --.' ...
,------.~
._--_._-------
.. -.. ----
.
MUNICIPAL WAStE M"OJSTURE EFFECT ON THEORETICAL
.
ENERGY PRODUCTION PER LB OF WETW ASTE
8000
70gg
6000
~ Sggg
~
"-
t:1
I
~
::l
~
NET THEORE.TICAL ENERGY
/
4090
ENERGY RELEASED (GROSS)
/
3099
I
UtAtT
Of'~PE1'ABIUTY Of Pt.ANT
I
~ 20BB
w
ffi 1BBB
ENERGY REQU,RE[I
~
FOR DISTIllATION"
"
.
9
-lBBg
:'2099
g
10
20
30
40
50
MOISTURE %
60
70
80
."
90
109
G)
c:
m
o
:0
I
Go)
d.
Efficiency of steam Energy Produced Versus Feed Rate
The effects of varying the waste feedrate and showing its
relationship to total steam production was studied experimentally
in a separate set of test runs. Results obtained from these tests
are presented in Figure 0-4.
The curve shown on Figure 0-4 indicates that no appreciable
steam energy is produced below a feed ra~e of 1100 lb/hr •• When
this feed rate is exceeded, the energy production increases with
increased feed rate, with a maximum value of approximately 2950
BTU/lb.. Identical results are shown in F[igure 0-5 which is a plot
of net energy produced per hour versus the feed rate of wet
municipal waste. Again we see that very little energy is produced
unt~il an 1100 lb/hr. feed rate is reached and then the energy
output continues to increase linearly.
In order to explain the increase of plant efficiency with
increased feed rate, two factors must b~ discussed.
The first
factor is what we call the "energy overheap." of the plant. This is
the. amount of energy required to have all of the steams of the
pla.nt heated to operating temperature. Energy must be used to heat
the, plant, and to sustain the process even though this energy is
exhausted in the hot flue gases or waste heat from the plant. The
second factor is that the plant is ineffi¢ient when the feed rate
drops below its design capacity.
One example of such an
inefficiency lies in the operation of the ,boiler. The boiler used
in the tests has a design rating of 35 MMBTU/hr. and is designed to
operate most efficiently in that range.
The air-to-fuel ratio
controller installed could not go below a certain minimum air
flowrate to the combustion chamber of the hoiler. Excess air beiing
fed to the boiler is shown in Figure 0-6 as a function of municipal
waste. feed rate.
It is obvious from the graph that the boiler
energy efficiency is very poor at low feed rates and that
efficiency increases as design capacities', are reached. Note also
that these low efficiencies begin to appear only when the plant is
operating below 50 percent capacity but, When operating at design
conditions of 5000 lb/hr. feed rate ineffli.ciency does not appear.
0-7
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--:'£,'-::;"~~",.;,.;;;;;E;;:~'-
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_._.~ _ _ _ _ _._ _ _ _ _ _ _ __
STEAM ENERGY VS. FEEDRATE
EFFICIENCY DEPENDS ON FEEDRATE
5300
4500
40G0
~
3500
"-
ASYMPTOTIC
~ 30UO
t:l
I
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.
VALUE: 2,950 BTUIIB
~ 2500
•
IX:
W
zw 2000
•
1500
A
A
•
leg0
•
A
500
0
.-----,------r-.--
0
-I - -
TEST RESULTS A
TEST RESULTS B
----I----~.,------..,
500 1990 1500 2000 2500 3900 3500 4gg0 4500 5000
FEEDRATE LBtHR
I
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)TOTiAL ENERG't!~V.s. FEEDRATE
EFFiCiENCY DEPEi~6'S ON·FEEDRATE
12
11
19
0:
i:'
;'-'~.
=>C,)
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• TEST RESULTS A.
.. TEST RESULTS B
o
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lOgO
:'15g0'2gQg\",,~:l}25'CG,'
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.. ". .' ....
FEEDRWTB,itB'1HR
".,_·y";~::i~t~"'hf:'
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. 4000
4500
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e.
Operational Characteristics of the Dryer
Experiments were performed to analyze MSW for moisture content
at the input and output ends of the dryer. Results indicated that
the dryer is heat-transfer limit~d under design conditions and was
removing between 130 and 210 pounds of water per hour. The product
of the heat-transfer co.efficient and the area of the dryer was
calculated from the experiment; The value of U x A is 933 BTU per
degrees F for a heat exchange area (A) of 622 square feet, and an
overall heat-transfer coefficient (U) of 1.5 BTU per hour, per
degrees F, persquarefpdt.
The dryer, under present design
conditions, typically removes 10 percent. of the t'otal moisture from
the MSW. 'The heat-trans:fe'r model. of the dryer was incorporated
into the simulate~ IIIod~l of the plant ana calculations were made, to
establish .steam prc;>dllctj,ohat varying moistures.
Table D-3aad
Figur~D-1 show the limit'ing effect of.moisture on total steam
ener91 ,produced.
\1.1'
,,_,
,.,'
,
'\
It is recommended that municipalities take precautions to
reduce excessive moisture in the "as received" municipal waste 10
increase steam production. The plant· s drying capability can still
be:;;;;improv~d. by better utilization of the waste heat streams.,
'
.
I
0-10
BOILER EXCESS AIR
DEPENDED UPON FEEDRATE
SgG
45G
4gg
.,p.
ex:
3Sg
«
309
I
en
en
250
I-'
I-'
()
2g9
t:1
w
><
w
•
,
q
, ~q
i
,j
.":
•
TEST RESULTS
1
15Y
"
lOG
I
II
!
sG
0
2000
2250
2500
FEEDRATE LB/HR
\
2750
3009
"TI
c:>
C
::0
m
t:1
I
~
I
r
~
TABLE
0-3
LB. STEAM/HR.
MOISTURE IN
MSW 'lrl
5
10
15
20
25
30
35
40
65
15855
14524
13192
11851
10504
9150
7792
e
17154
55
14552
13460
12352
11234
10106
8974
7835
6692
Z
o
50
13253
12264
11261
10244
9225
8201
7173
6137
w
45
11946
11060
10166
9263
8356
7435
6508
5580
!<a:
35
9323
8646
7962
7270
6572
5868
5159
4446
25
6686
6200
5733
5245
4759
4270
3774
3276
>..:
(/)
I-
o
---
W
W
LL.
il
'\
I,
:l'I
IIt~
FIGURE 0-7
·STEAM PRODUCTION
I
2gBBB
I.
I,
18BBB
II
I
~
II~
ij
"
~i
R
),1
Ii
t3
U
i~
"I
'1
fJ,
n
H
f-"
If'B
65
1609O
. 14BOB
55
Cf)
-
0:
:J:
50
45
120BB
<
UJ 10BGO
fCf)
8GOG
CD
..J
60GB
40gB
~
::~
--
20GB
0
....
0
5
10
15
2S
30
3S
40
MOISTURE OF MSW %
D-12
i
3.
A SIMULATION HODEL OF THE PLANT
The operational characteristics of the plant previously
described provided enough basic operating information about the
waste converter to develop a computer simulation model of the
plapt.
Information concerning the material and energy balances
.each of the streams of the plant were then calculated under various
ope~rating condition (Refer to Figure 0-1:
Flowsheet of the Plant).
The key unit of equipment in the plaQt is the waste converter
assumed to be operating at a fixed temperature of 1150 oF.
Thi.s temperature was found in actual tests to be high enough to
produce a high volatile conversion rate ~ and yet not stress the
retort material which in turn extends th~ life of the equipment.
Using this 1150 0 F temperature, conversion! energy of the volatiles
andl the conversion of atomic species werEi assigned the values set
forth in the previous section.
The waliite converter furnace or
firebox was assumed to completely oxidizE! all carbon atoms to CO 2
since the emission of CO and hydrocarbons was almost negligible in
the testing of the plant. All sulphur present in the produced gas
converted to 502 and 50 3 while all hydrogen atoms was converted to
water (See Table 0-1 and 0-2).
All bther coagulations were
performed from the exact material and eneirgy balances.
and~as
The combustion chamber of the boiler was calculated using the
Sallile assumptions as in the converter furnape above. Boiler exhaust
gases were assumed to leave the boiler at ~60oF, a temperature that
was consistently observed during expeirimental runs.
Other
calculations were based upon the exact material and energy
balances. Using the above assumptions and, applying mass and energy
balances in all splitters and mixers, the ',model was implemented as
a template in a personal computer advanced spread sheet program.
The iterations required in all recycle' loops were numerically
unstable and required convergence algorithms to obtain the steady
state value.
Figure D-8 shows a set of actual e~perimental data of net
energy produced in the form of steam compared with simulated
results obtained for values of the excess air in the boiler
calculated using the graph in Figure O-~.
The fit between the
experimental data and the simulated mddel is quite good and
therefore, the model can be used to provide material and energy
balances in the plant under different operating conditions.
4.
MATERIAL AND ENERGY BALANCES AT THE DESIGN CONDITIONS
Table 1 (Appendix 1) gives the materi?l and energy balances of
the plant as set forth under design conditions:
65 tons of wet
municipal waste/day (5416 Ib/hr), at 35 p~rcent moisture,. with 30
percent excess air in ;the boiler and waste converter combustion
chambers. Steam production is predicted 'to be a minimum of 9149
D-13
lb/hr (refer to Figure D-1 for stream numbering information) and as
moisture content is reduced steam production increases.
5.
MATERIAL AND ENERGY BALANCES UNDER
ENVIRONMENTAL TEST CONDITIONS
Table 2 (Appendix 1) gives the material and energy balances in
the plant utilizing the conditions found in the environmental tests
performed on November 7, 1984~ Note that in the Table the energies
are given in BTU/hr, masse's in lb/hr. The municipal waste was fed
intothewasteC()nverte;t:at,a rate of 4000 lb/hr, and contained 28
percelltmoi;;tui',e. 'i " T:ne::,r~isul't!3. of emission tests and those
calculated from .,the simula'tibn, pt6<;Jram are compared in Table D-4.
TABLE D-4
SIMULATiON
,
MEASURED
20.00 lb/nr
20.00 lb/hr
4.12 Iblh,r
,
3.50 lb/hr
,
Particulates
,,
'L
5.60 lb/:hr
It
0.00
lb/~~
D-14
5.60 lb/hr
ND
COMPARISON PLANT SIMULATION
WITH ACTUAL PLANT RESULTS
50g9
4500
i: 43BB
In
~
a
35B0
~ 30g0
::J
,
tl
......
lJ1
ga:
2530
>-
2000
0..
(!)
~ 1500
w
10B3
/
SIMULATION MODEL
•
TEST RESULTS
533
3
t533
1750
2030
2250
2500
FEEDRATE LB/HR
.-.. . ----- -'.'- .. -.-..
275g
3g00:!!C>
§5
m
o
tl,
I
SECTlON E-
t
f
I:
1
SECTION E
ENVIRONMENTAL STUDY
1.
MUNICIPAL SOLID WASTE AND SOLID RESIDUE
a.
Introduction
On November 7, 1984, a series of environmental tests were
conducted on waste converter uni t locat~d at Elmwood Park, New
Jersey.
b.
Municipal Solid Waste
About 25 percent (by weight) of all MSW in America is
comprised of water, with the balance primarily consisting of paper,
food scraps, metals, and glass containers. MSW has been sorted,
packed, weighed, and analyzed for years..
Figure E-l shows the
composition of a typical MSW. 2
During the environmental testing of t~e waste converter, seven
samples were taken of the "as received" I1SW feedstock.
The MSW,
utilized in the testing, was obtained from the Monmouth County
Reclamation Center, Tinton Falls, New Jersey and consisted of a
residential-commercial type waste.
As ~art of the testing, a
pro:x:imate
analysis,
ultimate
analysis,
and
hazardous
characteristics analysis were conducted on the waste. The results
of these analyses are presented in Tables E-l through E-3.
Addi tional information regarding MSW testing can be found in
Appendix 2.
I
2 Carr ier Corp Contract to Syracuse ~niversity' s Professors
Drucker and Heimburg, 1976.
E-l
FIGURE E-1
TYPICAL COMPOSITION OF MSW
NON-BIOMASS
PRODUCING
. PORTION
BIOMASS
LEGEND
ENERGY PRODUCING
.7
~ PAPER, GARBAGE, YARD WASTE
7 •• ~ LEATHER, RUBBER, Tt:XTI~ES.
WOOD, PLASTICS
NON-BIOMASS
2S ~ MOISTURE
'Hl.e1l'o GLASS. FERROUS META~
. . . NON-FERROUS METAL.
_ _ _ OTHERS
I
100 ..
E-2
TABLE E-1
Moisture
Ash
volatiles
Fixed Carbon
MSW PROXIMATE ANALYSIS
Percentage
By Weight
29.80
19.87
44.79
5.54
100.00
Heating Value:
As received
Moisture free
4,874 BTU/lb
6,943 BTU/lb
6.7 lb/ft 3
Density:
TABLE E-2
MSW ULTIMATE ANALYSIS
Percentage
By Weight
32.17
7.34
19.42
0.40
0.23
0.18
12.26
28.00
Carbon
Hydrogen
Oxygen
Nitrogen
Sulfur
Chlorine
Ash
Moisture
100.00
Dibenzodioxins
Dibenzofurans
ND*
ND*
I
*ND = not detected; detection limit is approximately 10 mg/kg
E-3
TABLE E-3
MSW HAZARDOUS CHARACTERISTICS ANALYSIS
Ignitability
waste will not ignite "as is" because of
its high moisture content (1)
Corrosivity
pH is between 2-12(2)
Reactivity
less than .0001 percent of sulfide(3)
less than .0001 percent of cyanide(3)
(1) Per 40CFR261.21
(2), waste
characteristics of ignitability.
does
not exhibit hazardous
(2) Per 4 OCFR2 61. 2 2
( 1), waste
characteristics of corrosivity.
does
not
exhibit hazardous
(3) Per 40CFR261.23
(5), waste
characteristics of reactivity.
does
not
exhibit hazardous
c.
Solid Residue
1)
Conventional Incineration Residue
Major water quality compliance problems are associated with
most incineration, RFD-fired boiler plants, and mass burning
processes. These problems stem from heavy metals contained in the
bottom ash which in turn can contaminate water discharges. This
wastewater condition requires treatment before discharge into a
sanitary sewer system or a receiving water. Also water-saturated
ash retrieved from the main quenching troughs of some incineration
systems requires that toxicity tests be performed to ascertain the
toxicity· of the ash before deposit in a landfill where harmful
materials could leach out.
If any ash residue is found to be
toxic, then disposal falls under the guidelines set forth by the
Resources Conservation and Recovery Act (RCRA), whereby the residue
must be manifested (tracked) and disposed of in an approved
hazardous waste disposal site.
(2)
Char and Solid Residue from the Waste Converter
This section considers the environmental impact upon a
landfill in disposing of ~aste converter char residue versus
disposal of bottom ash and fly ash residue produced by conventional
or mass-burn incinerators.
The dry distillation of MSW yields a volatile gas and a solid
residue. This residue (residual char) contains a mixture of' highly
polymerized organic matter and inorganic components, intimately
E-4
agreggated.
This solid residue consists of 30 to 50 percent
carbon, and constitutes 21 percent of tne total original mass of
unsorted municipal waste fed to the converter.
Due to high temperature treatment d~ring the dry distillation
process (over 1000 0 F), the solid residue is completely sterilized.
The process temperature and long residence times make the survival
of bacteria and germs impossible.
During testing of the waste converter unit, three separate
char residue samples were taken during each of three runs. A part
of the testing, the following were conducted:
(1) proximate
analysis giving percentage by weight of,moisture, ash, volatiles
and carbon and also heating value and density; (2) ultimate
analysis giving percentage by weight of ~lements, ash and moisture
and also findings with reference to dio.xins and furans; and (3)
hazardous
characteristics
analysis
~ndicating
ignitability,
corrosivity, reactivity and EP toxicity.
The result of these
analyses are presented in Tables E-4 through E-6.
Additional
information regarding the char residue testing can be found in
Appendix 2.
3)
Volume and Weight Reduction
The treatment of municipal solid was',te Hi the waste converter
has the overall effect of greatly reducing the "as received" volume
of the biomass or organic matter as well as concentrating it in
form.
This reduction in volume takes place due to two factors:
the major factor is the reduction of mass due to chemical
conversion of biomass in the converter and another reduction factor
is due to an increase in the density of the solid residue through
densification
such as, the crushing of glass Table E-7
illustrates these two components as 'they relate to volume
reduction.
This volume and weight relationship of MSW and char
residue is graphically depicted in Figure E-2.
d.
ABSENCE OF DANGEROUS POLLUTANTS
Laboratory analysis of the waste converters solid residue
using EPA Method 25 (G.e./M.S. screen) failed to detect any traces
of Dibenzodioxins or Dibenzofurans.
1)
ehar Encapsulation of Leachable Materials
During the dry distillation processing of f.fSW, the solid
residue is exposed to high temperature and hot organic vapors as
well as hot hydrocarbon gases.
These conditions tend to form a
layer of polymerized organic coke material on the surface of the
various particles making up the solid residue.
E-5
Upon completion of the distillation phase, the individual
solid residue particles have been encapsulated by this polymeric
coke layer preventing the free dispersion of dangerous pollutants
into the environment.
Asa consequence of this encapsulation
process, it is difficult for such chemicals to leach out from the
waste converters char residue.· The conventional incineration of
MSW creates no such protective capsule and over time leaves the
Chemicals exposed to the weathering action of water and oxygen
.which can dissolve these pollutants and contaminate underground
water.
To. give credibility to the above explanation and set forth the
environmental advantages connected with the char residue produced
by <iry distillation of MSW over ordinary ash, an experiment was
performed (See Appendix 2).
In this experiment a test sample of
solid char residue was taken from the. waste converter and divided
in!to', two parts.
One of these parts was incinerated and .the
z;esuitant 'ash. was sUbjected to EP' toxicity tests using distilled
:wa't!er~ . The unburned portion of 'solid char residue was treated
1,ilk:ew'ise.
The leachate fr.ombot~ samples WaS analyz.ed for .the
priio.~ity pollutants using. the RCRAmethod (Federal Register May
19, .. 19'80).
There were no toxicdrganic pollutants found in the
prior analysis of the solid char residue, therefore, both leachate
tests indicated no. detectab~~ '.'1, amounts of endrin, 'lindane,
methoxyclor, toxaphene, 2,4-D or 2,4,5-TP Silvex. The results of
tqe i~est perfqrined to det ec1:.11e)k:tyY; metals found· in 'the leachate of
. tl~e ,~mburIled solid ch~rresidue!'a.nd those. found in;theleachate of
1ip'~ "~sh oLtheincinerate<i soli!4:'icharresiJdue the results! ,given in
r:p,!a:Pl~ E - S . " , .
i
E-6
VOLUME & WEiGHT REDUCTiON OF MSW
97" VOLUME REDUCTION
1:1:1
I
'}/j
~
"')1
L~~-i
.~
\1
Ej
',,9,"
ONE CUBIC FOOT
48 LBS. RESIDUE
J
I
34 CUBLIC FEET
MSW 229 LBS.
-c
."
I
Ii
G>
::0
m
r
it:
m
I
I\)
f
I
~
TABLE E-4
CHAR PROXIMATE ANALYSIS
(Average of Three Samples)
Percentage
By weight
0.13
66.44
5.S4
27.60
Moistu~e
Ash
Volatiles
Fixed Carbon
100.00
~t
,
Heating Value:
as-received
moisture-free
3,799 BTU/lb
3,S04 BTU/lb
Density
with inerts
4S lb/ft 3
TABLE E-5
CHAR ULTIMATE ANALYSIS
(Average of Three Samples)
Percentage
By Weight
39.S9
0.79
Carbon
Hydrogen
Oxygen
Nitrogen
Sulfur
Chlorine
Ash
Moisture
0.52
0.31
O.BS
56.62
0.98
100.00
ND*
ND*
Dibenzo-p-dioxins
Dibenzofurans
*ND
= not
detected: detection limit is approximately 10 mg/kg
E-S
TABLE E-6
.
CHAR HAZARDOUS CHARACTERISTICS ANALYSIS
19nitabili ty
char will not readily ignite
by open flame, by friction,
nor by elevated temperatures(l)
Corrosivity
pH is between 2-12(2)
Reactivity
less than .0001 percent of sulfide (3)
less than .0001 percent of cyanide(3)
(1 )
( 2 ) , waste
Per 40CFR261.21
characteristics of ignitability.
does
not
exhibit
hazardous
(2)
Per 40CF.R261.22 (l) ,
waste
characteristics of corrosivity.
does
not
exhibit
hazardous
(3)
Per 40CFR261.23
(5) ,
waste
characteristics of reactivity.
does
not
exhibit
hazardous
E-9
TABLE E-7
MSW VOLUME AND WEIGHT REDUCTION
PRINCETON TESTS:
1 ft 3 MSW
1 lb MSW reduces to:
1 ft 3 Char and Residue
=
=
6.70 lb.
.21 lb. residue
48.00 lb.
THEREFORE:
1 ft 3 MSW at 6.7 lb. x
.21 lb.
. residue
= .L.!
lb. char and solid
AND:
1 ft 3 Residue at 48 lb.
1. 4 lb.
=
34.3 ft 3 MSW x 6.7 lb/ft 3
=
AND:
229.8 lb
When reducing 34.3 ft 3 of MSW weighing 229.8 lb. to ft 3 of residue
weighing 48 lb. the results are:
MSW Volume Reduction
RATIO:
97 percent
=
79 percent
34:1
MSW Weight reduction
RATIO:
=
5:1
TABLE E-8
Heavy Metal Concentration - mg/
Arsenic
Barium
Cadmium
Chromium
Lead
Mercury
Selenium
Silver
Leachate of Unburned
Solid Char Residue
Leachate of Burned
Solid Char Residue
ND
0.82
0.02
less than 0.02 (ND)
0.09
ND
ND
ND
ND
1.10
0.08
0.04
0.31
ND
ND
ND
E-IO
% Increase of
Heayy Metal
+ 0
+ 34
+200
+400
+244
+ 0
+ 0
+ 0
· The aIIlount of heavy metals leached from ash derived from the
incinerated sample of solid char residue is much higher than that
leached from the unburned sample of solid c.har residue.
It is known that bottom ash, as well as the fly ash collected
from
electrostatic precipitators
installed in conventional
incinerators, are high in ~oncentrated heavy metals and must be
continually monitored before deposit in a landfill.
The
encapsulation of heavy metals in the solid char residue could prove
to be a very desirable environmental advantage that the waste
converter would have over ash disposal pr9blems associated with
conventional incineration.
It would also appear that although a
20-percent increase in energy output of the waste converter could
be obtained by burning the char residue in an incinerator, this
procedure would not be the best use considering both air pollution
caused by the incineration and the potential adverse long-range
environmental impact of heavy metals on wat\er supply systems.
2)
The retention of Chlorine in the Solid Char Residue
Relating to Dioxin and Furan Emissions
It is believed that chlorine contained in municipal solid
waste plays a major role in the production of dioxin during
incineration. 3
The chemical process requires that chlorine
(probably as HCL) be present in the gas phase for dioxin to be
formed. In the waste converter, most chlorine atoms do not evolve
into the fuel gas, but remain chemically bbund to the solid char
(refer to "Conversion of Chemical Elements Present in the Waste") •
Polychlorinated dibenzodioxins (PCDDs) are a family of
compounds consisting of two benzene rings! joined by two oxygen
atoms and having from one to eight chlorine atoms attached around
the rings. There are 75 chlorinated dioxids which differ in; the
positions or number of chlorine atoms.
The tet.rachlorinated
dibenzodioxins (TCDDs) are the twenty-two different dioxins
(isomers) having four chlorine atoms. The ilsomer known as 2,3,7,8TCDD has chlorine atoms at the locations nuttIDered 2,3,7 and 8. The
polychlorinated dibenzofurans (PCDFs) are a/very similar family of
compounds differing in that only one of :the bonds between the
benzl~ne rings contained an oxygen atom. Tfue nomenclature for the
chlorinated dibenzofurans is completely an~logous to that for the
dibenzodioxins.
'
!
3"Emissions and Emission Control
Incinerators," Battelle s Columbus
Ohio 1981.
I
E-ll
j
in
Modern
~aboratories,
Municipal
Columbus,
In the
dry distillation process,
!lQ
polychlorinated
dibenzodioxins or dibenzofurans were detected in any of the solid
or gaseous product streams. The success of the waste converter in
not producing dioxin is primarily due to the careful regulation of
the process temperature and the oxygen-free atmosphere of the
converter, which prevents the burning of MSW in the presence of
chlorine.
e .POTENTIALUSE/RESEARCB FOR SOLID RESIDUE
The solid residu.e .froDl·waste conversion contains about 50
percent c:arbon.
Potentialutilizati9n' for this product has not
beenacthrelY' pursued in this ,study • . ,!=onsideration for use as
activ'ated carbon is. an,!area:,ltcha;t . wa;rrants early. consi,deration
beca~s: its bElnefic:iaLu,ses ~s l.an';aDsorbent has significant
potent~ail..
"" ' "
'
.
,
f.
CONCLUSIONS
1)
A solid residue is left after dry distillation of
municipal solid waste. It constitutes about 3 percent of
the in~tial waste volume which would be higher that the
volume of ash produced by complete incineration. Volume
redu.ctionof "aiS received" MSW was 34:1.or 97 percent; a
Weightii'reduction of '!as received" MSW was 5: 1 or 79
percePiL
2)
The high temperature treatment of the waste and the longresidence times dill all bacteria and germs contained in
the municipal waste • The solid residue leaves the waste
convertericomplete1y., sterilized.
1!1
3)
In the dry distillation process, solid particles are
enc:apsulated with a layer of polymeric coke; this coke
layer shields inorganic components, making them more
difficult to dissolve when the residue is exposed to
water, and;, oxy:gen.
As a· ):"esul t, the waste converter' s
,sdlIJLd:ic:halrresidue will; yield a smaller fraction of heavy
metaJl,~, that
the; natllral leaching. of conventional
in6l:Ltterator ai;h wheo':jE!xp6sed to, the elements •
.
4)
!
t
j
I,.
",
Most c:hlorine atoms present in municipal ,?01i4 waste
(mainl-y originating from plastics) remain in an inactive
form and are 'retained or encapsulated within the solid
char ):"esidue.
This prevents the chlorine atoms from
participating: in chemicial reactions where the formation
of new compolfhds -- such as, dioxin -- could take place.
This fact,:Ln ' turn, insures that stack gases, as ,well as
the Isoliid clia:rresidue ,produced by the waste conv.erter,
are:dlotxih,[f!i:iee.
E-12
2.
,a.
STACK EMISSIONS
Introduction
Air pollution stack testing was carried out in accordance with
methods and procedures established by the u. S. Environmental
Protection Agency (EPA) and the New Jersey Department of
Environmental Protection (DEP).
All samples were taken from a
conunon stack serving the: drying unit, converter unit, and boiler.
This stack had no pollution-control devices installed for the
relllloval of air contaminants.
Table E-9 summarizes the results of t.he air pollution testing_
Since during the tests no pollution contro.l devices were installed,
the data presented is representative of the technology's
uncontrolled n uncontrolled "potential" emissions.
Furthermore,
since the data was collected from a common stack, it includes all
source emissions from the facility.
Additional information regarding the air pollution testing can
be found in Appendix 2.
b.
Emission Standards
Under current air pollution regulations pertaining to
Prevention of Significant Deterioration (PSD) and Nonattainment
.Area New Source Review (NSR), specific numel..Lcal emission standards
are not defined for a new source.
Instead, each proposed new
source must propose emission limits that reflect Best Available
Control Technology (BACT) for PSD and/or Lowest Achievable Emission
Rate (LAER) for NSR for the control of air contaminants.
The
appropriate environmental regulatory agency then reviews on a caseby-case basis the proposed emission standards and considering
economic, energy and environmental impacts, determines whether or
not the degree of control reflects BACT and/or LAER and is
sufficient to protect human health and the environment.
E-13
TABLE E-9
AIR POLLUTION TESTING RESULTS - UNCONTROLLED EMISSIONS
waste Converter
Emission Rate
(lbs/ton.)
Pollutant
Particulate
..
!
j
~1
"I
I
!
50 2
50 3
HCL*
CO
NOx
Volatile Organic Substances
Condensable
Non-condensable
Fontl<3:ldeh yde
Lead
Beryllium
Mercury
Nickel
Chromium
Arsenic
Cadmium
Dibenzodioxins
Oibenzofurans
*Obtained by Material Balance.
E-14
9.170
1. 840
8.400
0.480
0.881
2.660
0.163
0.121
.0004000
.0079200
.0000245
.0000214
.0006200
.0026400
.0001340
.0005630
none detected
none detected
Although no specific universal emission standards are
available, some state air pollution regulatory agencies have
developed general emissions guidelines for new resource-recovery
facilities. These are used to assist the agencies in setting BACT
and or LAER requirements. . Since the waste converter unit was
located in New Jersey, that state' s emissions guidelines were
considered.
Table E-10 presents a summary of 'the emissions
guidelines imposed by the State of New Jersey on new resourcerecovery facilities.
.
c.
Uncontrolled Emissions
Rather than to rely on any vendo:rs claim or guarantee
concerning BACT, the tests performed ~n t~e waste converter were
conducted
to
set
forth
the
maxl.mum
predictable
adverse
environmental impact that the general public could be exposed to if
all control technology of the facility failed.
Therefore, all
emission tests were conducted with no; pollution control devices
installed on the waste converter.
These: test results were then
compared to the uncontrolled emissions. data of a mass-burn
incinerator 4 • In an attempt to set forth: this analysis in clear
terms, the number of pounds of each p011ut;ant emitted by each ton
of lnunicipal solid waste for each procedure was calculated and
compared on a percentage basis (See Table !,E-11) •
1)
Particulates
One of the products of thermal decon:1position of MSW in the
wast.e converter is a hot gas which contains vaporized tars, oils,
wateir and suspended char. When this gas is burned, the vaporized
tars and oils produce particulate.
4Source:
"Air Pollution Control at Resource Recovery
Facilities"; California Air Resources Board; 24 may 1984.
E-15
'fABLE E-lO
Pollutant
Guideline
Particulates
.02 qr/dscf, 3-hour average during non-soot-blowin9
.03 qr/dscf, i-hour average during soot-blowing
iOO ppmv, i-hour average or
70 percent reduction by weight
200 ppmv, 3-hour average
300 ppmv, i-hour average
co
~oo
VOS, as CB4
LAER, if emissions exceed 50 tons/year
BeL
ppmv, i-hour average
50 ppmv, i-hour average or
90 percent reduction by weight
Note: All concentrations are based on dry standard flue gas,
corrected t~ 7 percent 02. PPMV = parts per million in volume.
E-16
TABLE E-ll
AIR POLLUTION TESTING RESULTS - UNCONTROLLED EMISSIONS
Incinera-tor*
Emission Rate
(lbs/ton)
Waste Converter
Emission Rate
( l:bs/ton)
Percent Reduction
in Pollutant-Generation of the
Waste Converter
pollutant
Particulate
S02
50.0
9:.17
82%
3.9
~.84
53%
not reported
5°3
BCL
8.40
7.7
0.48**
94%
CO
7.7
C).881
89%
NO x
4.4
2.66
41%
Volatile Organic
Substances
Condensable
Non-:-ondensable
E'ormaldehyde
0.284
0.21
not reported
not .reported
Lead
.370
Beryllium
.00008
Mercury
0.163
22%
0.121
.0004
.007
98%
.• 00002
69%
.002
.00002
99%
Nickel
.010
.0006
94%
Chromium
.020
.002
87%
Arsenic
.005
.0001
97%
Cadmium
.040
.0005
99%
Dibenzodioxins
not reported
none detected
***
Dibenzofurans
not reported
none detected
***
*Source:
"Air Pollution Control at Resource Recovery Facilities";
California Air Resources Board; 24 May 1984.
**Obtained by Material Balance.
***Traces of Dibenzodioxins and Dibe:l1zofurans have been identified
in the emissions from a number of incinerators abroad and in
the U.S..
Testing results showed that no Dibenzodioxins or
Dibenzofurans were detected in the Waste Distillator- stack
gases.
A comparison of emissions data, Table E-11, shows uncontrolled
particulates to be 50 lblton of MSW for. incineration versus 9.17
lblton of MSW dry distillation.
This indicates that the waste
converter generates about 82 percent less particulates versus
typical mass-burn incinerator.
2)
Sulfur Dioxide
Sulfur dioxide emissions from incineration are a function of
. the amount of sulfur in the solid waste.
An average municipal
refuse has been found to contain approximately 0.12 percent
sulfurs on an as-received basis.
Not all of the sulfur in ithe
refuse appears in, !the' flue gas as S02when the refuse is
incinerated. Dependin<Jupon the type of incinerator and the form
of the sulfur in thewas'te., betwee.n 40 and 80 percent of the sulfur
is retained in the 'a:s~. 'ii The MSW used in the waste converter tests
cont,iined .23 perc~ptsulfur, TaBle E-:-2, by weight on an asreceived basis.
'.
A comparison of emissions data shows uncontrolled sulfur
dioxide emissions to be 3.9 lb/ton of MSW for incineration versus
1.84 lblton of MSW dry distillation. This indicates that the waste
converter generates about 53 percent less sulfur dioxide versus a
typical mass-burn incinerator.
3)
"
:-1
Nitrogen Oxides
The emission of nitrogen oxides from combustion sources is due
to either the conversion of nitrogen in the fuel to nitrogen
oxides, or to the fixation of atmospheric nitrogen at high
temperatures.
Combustion techniques applicable to fossil fuelfires boilers either are generally not applicable to the massburning of MSW or tend to cause higher CO emissions and
unacceptable boiler corrosion.
MSW used in the waste converter
tests contained .40 percent nitrogen by weight on an as-received
basis.
A comparison of the emissions data shows uncontrolled nitrogen
oxides emissions to be 4.4 lblton of MSW for incineration versus
2.6 lb/tonof MSW for dry distillation. This indicates that the
iwaste converter generates 41 percent less nitrogen oxides versus
a typical mass~burn incinerator.
'.
S"Emissions and Emission Control in Modern Municipal
Incinerators," Battelle's Columbus Laboratories, Columbus,
Ohio 1981.
E-18
4)
Carbon Monoxide
Carbon monoxide is a product of incomplete combustion and
depends largely on the overfire air rat;io, the design of the
overfire air jets and combustion temperatures. When volatile gases
produced by the dry distillation process are combusted in a boiler,
standard combustion techniques are applied to control carbon
. monolxide •
A comparison of emissions data sho~s uncontrolled carbon
monoxide to be 7.7 lb/ton of MSW for inqineration versus ~B81
Ib/t,on of MSW for dry distillation. This indicates that the w,:;,ste
converter generates 89 percent less ca~bon monoxide versus a
typi.cal mass-burn incinerator.
'
5)
Hydrocarbons
Hydrocarbons appearing in the flue gas of an incinerator are
products of incomplete combustion. They are mostly low-molecularweight hydrocarbons, aldehydes and organjjc acids with traces of
high molecular-weight compounds.
No municipal incinerator known
uses any type of add-on control device: to reduce hydrocarbon
emissions.
When the volatile gases' produced by the dry
distillation process are combusted in a boiler, standard combustion
techniques are applied to control hydrocaz!bons.
Comparison
shows
uncontrolled
condensible
hydrocarbons
emissions to be .21 lb/ton of MSW for ibcineration versus .163
lb/ton of MSW for dry distillation. This indicates that the waste
converter generates 22 percent less condensible hydrocarbons versus
a typical mass-burn incinerator.
6)
Hydrochloric Acid
Flue gases from municipal inciner~tors normally contain
hydrochloric acid as a by-product of the combustion of PVC, other
chlorinated plastics and sodium chloride found in the waste
Hydrochloric acid emissions are not regula:ted by the U.S. EPA, but
mos1t states require the emissions to b~ reported and control
regulations are under consideration in several states.
,
7)
Sulfuric Acid Mist
Very little data is available on emissions of 503 mist from
municipal incinerators. Sulfuric acid mist will be a vapor at high
temperatures but, especially in the presence of moisture, will
condense as an aerosol at lower temperatures.
8)
Polychlorinated Biphenyls (PCBs)
PCBs have been found in trace amounts in several municipal
incinerator emissions.
These materials probably result from
E-19
incomplete destruction of traces of PCBs found in the waste feed.
Since the manufacture and distribution of PCBs is now prohibited,
the amounts found in the refuse should decline.
9)
Heavy Metals
In mass-burning facilities the amounts of volatile and nonvolatile metals emitted in the flue gases will depend upon the
. efficiency of the particulate control system.
According to
studies, most "metals' with' ,the exception of mercury appear to
concentrate ,ihthe . bottom ',aSlh . and ,fly ash of. cC:>Ilventional
incinerationpnits. buring 'the clrY,distillatioh processing of MSW,
the solid .residue is.exposedtoll,igh ,temperature and hot organic
vapors as well as ,hothYdr~cill.rbon gas~s~, These conditions tend to
form a layer of· polymerized orgflni'cco~emate:tial on the surface
areas of all the .various par.ticies inclpdinc;J : metals making up the
s,olid residu~. ,. UpoIl; coIllpletion ofth~ dry. dist:.i.Uation. phase, the
i#di vid.~al:sldli~'resi,a:~~pa:!t~iclelsy,Qay~, iibeen '. eJ:}capsulated by this
polymer:i:Jd,';pF>k~i'IJiay;~tJ!I':~~;#"!i!~~titirlg:::njth~'i(;ldi,sp~r~ion ,of' dangerous
p o....,r+
'."1,',..tita.'.'D
1:.0., '.I.,.,.tfi.":~.', '.:ie..11."':. );!Jjb,.:.Me.'
~.'t.,L.'J!, '. lte. If~r;I,.)Ii!;O.'
"'.ls.''.e.,ct,iort,c.'
" '. ,ts,
,..'jli!in.'.'
i
",~I,'
" j ' h ' .. ,1."
'
,~, of t:h. is rep· o.rt
1'~'$~nd:~"i~f'~b~ri9'ercDti's:'P:6]ll;iU~antlsl~i;, ~jl:J:iq~r:i:suilation of., Leach~ble
Materials ~'" II'd i ,'.' Ii I! ',' . ,: 'r" ,'fir
,',
,.
',
,
I,
l.
,
:
I
'I
"
'~:
"
":,
,.•
','
,
I
,I,
'.,
I
j
',
ir~ble;E-12 i!lhows a cd~;ar1son for thetincontrolled heavy metal
emissions from MSW i=ncin~:tation'versus dry dis,tillation of MSW.
Emissions
-~
Pollutant
Lead
Beryllium
Mercury
Nickel
Chromium
Arsenic
Cadmium
10)
Incinerator 6
Emission Rate
(lbs/tonl
.37000
.{)o008
.00200
.01000
.02000
.00500
.04000
Waste Converter
Emission Rate
( lbsltonl
.,0079200
,,0000245
.0000.214
.,0006200
.0026400
,'e 000134,0
.0005630
Percent Reduction
of Pollutants Generation of the
Waste Converter
98%
69%
99%
94%
87%
97%
99%
Dioxins and Furans
Traces of polychlorinated dibenzodioxins and dibenzofurans
have been identified in the emissions from a number of municipal
incinerators abroad and in the u.S. In 1981 in response to reports
6Source:
"Air Pollution Control at Resource Recovery
Facilities," California Air Resources Board, 24 May 1984.
E-20
that dioxin compounds were found in emissions from facilities
burning municipal wastes, the u.s. Environmental Protection Agency
(EPA) issued a report, "Interim Evaluation of Health Risks
Associated with Emissions of Tetrachlorinated Dioxin from Municipal
Waste Resource Recovery Facilities" (USEPA, 1981a). The 1981 EPA
calculation of excess lifetime cancer risk for total TCDD was 8.4
x 10-6 •
The Tetrachlorinated dibenzodioxins (TCDDs) are the
twenty-two different dioxins (isomers) having four chlorine atoms.
In addition to icancer other potential health effects have been
associated with the dioxin and furan compqunds.
EPA made several assumptions in evaluating the health risks.
In summary, these were (USEPA, 1981a):
a)
The carcinogenic properties and ,reproductive effects of
all TCDDs are the same as that cif 2,3,7,8-TCDD.
b)
The PTMAX air dispersion model adequately represents the
transport of the emissions to g~ound level.
c)
The composition of emission p:ttoducts found at ground
level is identical to the composition (but not the
concentration) found in the stabk.
d)
Seventy-five percent of the inhaled emission particles
(to which the TCDDs are prefer~ntially and tenaciously
bound) are retained in the body~
e)
All the TCDDs that are retained in
biologically available to the o~ganism.
the
body
are
I
f)
The population is exposed to th.e maximum annual average
ground level concentration from the source for 24 hours
a day throughout a 70-year life~ime.
g)
Humans are the comparable sen!:;itivity to the animals
tested in the carcinogenic and reproductive effect
testing, taking relative body suirface areas into account.
I
h)
The excess lifetime cancer riskb are calculated for a 70
kilogram person who inhales 201 cubic meters of air per
day (USEPA, 198Ib).
.
Since 1981, changes have occurred in/the chemical analysis of
samples for chlorinated dioxins and furans and in the toxicological
data which can be used to estimate th~ health risks of these
chl3micals.
!
Based upon the EPA's verification that potential health risks
were associated with polychlorinated diberizodioxin and dibenzofuran
emissions eminating from mass-burning g~rbage plants, the major
interest of this testing was characterization of emissions from the
E-21
---_.__
._-_._- -
waste converter especially the organic compounds -- such as,
dibenzodioxins and dibenzofurans.
Testing results showed that no dibenzodioxins or dibenzofurans
were detected in the waste converter's stack gases or in its solid
residue.
3..
EMISSION CONTROL
a.
Complete Combustion
The ability to employ known standard boiler combustion control
techniques when firing the volatile gases produced by the dry
conversion proces.s greatly reduces the source of emissions. This
source reduction simplifies final flue-gas clean-up by a large
percentage.
b.
Mechanical Device
A supersonic scrubber manufactured by HydroSonic Systems
(Figure E-3) has been selected as best available control technology
and will be specified as original equipment to be installed with a
waste converter system. HydroSonic Systems have been tested and
will be installed in the U.S. Department of Energy's Defense Waste
Processing Facility under construction at the Savannah River Plant
in South Carolina. This proj ect is being managed by E.!. du Pont
de Nemours and Company (du Pont), with Bechtel National, Inc. doing
the o.etailed design.
Selected as the best available control technology for cleaning
off-gas from the vitrification of radioactive waste, HydroSonic
Systems had six prototype devices in operation at the Vitrification
pilot Plant being tested prior to selection as the air pollution
control device for· the main project.
HydroSonic Systems, manufactures a family of steam and
compressed gas scrubbers and fan powered free-jet scrubbers capable
of submicron particulate capture and toxic fume removal, such as
HCL, SOx' and NOx ' in the same process. The gas cleaner is a wet
scrubbing system employing a unique nozzle arrangement and mixing
tube to create thorough mixing of the gas stream with water
droplets for pollutant capture. Either a forced draft or induced
draft fan provides the driving force for the system.
Dirty gas is driven through a free-jet nozzle fitted with a
water infection ring.
Water is injected onto the driven gas
stream. Turbulent mixing occurs as the free-jet expands, causing
capture of particulate ranging from large to very fine sub-micron
sizes.
This mixing also provides an efficient means for
simultaneous 'capture of gaseous pollutants when proper reagents are
added to. the water. As the steam progresses through the mixing
tube, part:iculate-e'ntrained droplets collide to form larger sizes
for ease of separation.
Agglomerated droplets containing
pollutants are spun through cyclone sepprators, where the liquids
drop out to drain. Scrubbed gases are vented to atmosphere.
E-23
HYDRO-SONIC@SCRUBBER
SCRUBBING LIQUID
INJECTED
_._TURBULENT MIXING
OF GAS & ,LIQUID
l,'l:j
I
N
"'"
.....
,
.•• ",
~ e"
GAS INLET .....
;•...
.-
-, o'
:' ".("
•
.. . . .
,....
.
...
.
..:
"",
_.••.•~ ..•...•: :
.0,:-
.
..
..
'.
_.;: '"
~~":...
~':. ,~.'; ;....... :~ .." ~Vp
.
..
•
.
•
•
•
:::,::~, AGGLOMERATION
.\.. ~ :.
' : . . •••• •
...
..... . .... .,- .....": ...
I
FREE-JET NOZZLE
. . ..
MIXING TUBE
."
C>
C
lJ
m
m
I
(.J
j/
4•
CONCLUSION
Implementation of the above emission control technologies
should guarantee that the waste converter's controlled emissions
will be maintained at a level representative of Best Available
Control Technology BACT.
A comparison of these guaranteed
controlled emissions for a commercial waste converter facility to
be installed in the New Jersey emission guidelines as set down for
new resource recovery facilities.
E-25
TABLE E-13
COMPARISON OF WASTE CONVERTER CONTROLLED EMISSIONS
VS. NEW JERSEY EMISSION GUIDELINES
FOR NEW RESOURCE RECOVERY FACILITIES
Pollutant
Particulates
S02
NO x ' as N0 2
CO
VOS, as CB 4
BCL
New Jersey
Guideline
.02
100
200
400
gr/dscf
ppmv
ppmv
ppmv
.019 gr/dscf
90 ppmV
200 ppmv
245 ppmv
140 ppmv
40 ppmv
50 ppmv
0.13 lbs/ton
0.74 lbs/ton
1.19 lbs/ton
0.88 lbs/ton
0.28 lbs/ton
0.19 lbs/ton
Note:
All concentrations are based on dry standard flue gas
corrected to 7 percent O2 , PPMV = parts per million by volume.
E-26