EPA-600/2-76-090
April 1976
Environmental Protection Technology Series
CLEAN FUELS FROM AGRICULTURAL AND
FORESTRY WASTES
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution. This
work provides the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality standards
EPA REVIEW NOTICE
This report has been reviewed by the U.S. Environmental
Protection Agency, and approved for publication. Approval
does not signify that the contents necessarily reflect the
views and policy of the Agency, nor does mention of trade
names or commercial products constitute endorsement or
recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield. Virginia 22161.
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EPA-600/2-76-090
April 1976
CLEAN FUELS
FROM
AGRICULTURAL AND FORESTRY WASTES
by
J.W. Tatom, A.R. Colcord, J.A. Knight, andL.W. Elston
Engineering Experiment Station
Georgia Institute of Technology
Atlanta, Georgia 30332
Contract No. 68-02-1485
ROAP No. BJV-012
Program Element No. 1AB013
EPA Project Officer: J.D. Kilgroe
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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ABSTRACT
An experimental investigation of the operating parameters for a mobile
waste conversion system based on the Georgia Tech Engineering Experiment
Station partial oxidation pyrolysis process has been made. The object
of the testing was to determine that combination of parameters producing
the greatest amounts of char and oil and the least gas from agricultural
and forestry wastes. From the tests, the dominant influence of air/feed
on char and oil yields is apparent and the desirability of low values of
this ratio is clear.
In addition to the testing, a preliminary design of a 200 ton/day (assuming
a 50 percent moisture feed) mobile pyrolysis system for conversion of
agricultural and forestry wastes into clean fuels was made and a simpli-
fied economic analysis conducted. The results of this work indicate the
technical feasibility and the economic profitability of such a system.
This report was submitted in fulfillment of Project Number A-1653, Contract
Number 68-02-1485, by the Georgia Tech Engineering Experiment Station under
the sponsorship of the Environmental Protection Agency. Work was completed
as of March 1975.
ii
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CONTENTS
Abstract
List of Figures iv
List of Tables vi
Foreword viii
Sections
I Conclusions 1
II Recommendations 3
III Introduction 4
IV EES Experience in Pyrolysis 10
V Testing 23
VI Mobile Pyrolysis System Preliminary Design -^
VII References 71
iVIII Appendices 72
iii
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FIGURES
No. Page
1 EES Waste Converter Schematic 8
2 First Generation EES Pyrolytic Converter H
3 Wood Wastes Field Demonstration Unit—Overall View !3
4 Wood Wastes Field Demonstration Unit—Char Handling 13
and Storage System
5 New EES Pyrolytic Converter 15
6 Pyrolysis Tube Furnace for Bench Scale Experiments 17
7 Condensation Train for Pyrolysis Experiments 18
8 Mass Balance for Pyrolysis of Pine Sawdust and Bark 19
9 Heat Available from Pyrolysis of Pine Sawdust and Bark 21
10 EES Pyrolysis Unit Process Flow Diagram 24
11 EES Pyrolytic Converter—Feed Bin and Feed Conveyor 25
12 EES Pryolytic Converter—Close-Up of Feed System 25
13 EES Pyrolytic Converter—View of Condenser Train 25
and Afterburner
14 EES Pyrolytic Converter—Close-Up of Condenser Train and 26
Afterburner Showing Particulate Material Separator
15 EES Pyrolytic Converter—Close-Up of Unit 26
16 EES Pyrolytic Converter—Feed System Showing Pneumatic Valve 26
17 Schematic of Agitator 29
18 Mass and Chemical Balance Calculation Procedure 40
iv
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Figures Continuted
No.
19 Fractional Char Yields Versus Air/Feed Rate 46
20 Percent Available Energy in Char-Oil Mixture 47
21 Energy Breakdown of Pyrolysis Products ^
22 Heating Value of Noncondensible Gas 50
23 Effects of Feed Moisture on Available Energy 51
from Char-Oil Mixture
24 Mobile Pyrolysis System Concept 53
25 Mobile Pyrolysis Unit Process Flow Diagram "
26 Plan and Elevation Views of Trailer I ^6
27 Plan and Elevation Views of Trailer II 57
28 Plan View of Deployed Mobile Pyrolysis System 58
29 Elevation—Crossection Views of Mobile Pyrolytic Converter 60
30 Net Income of a Mobile Waste Converter with Varying 67
Capacity—Fuel Price $20/ton
31 Net Income of a Mobile Waste Converter with Varying 68
Capacity—Fuel Price $35/ton
32 Net Income of a Mobile Waste Converter with Varing 69
Capacity—Coal Price $50/ton
33 Net Income of a 100 Ton/Day (Dry) Waste Converter 70
with Varying Fuel Prices
QO
A-l Viscosity of Pine Wood Waste Pyrolysis Oil 3U
A-2 Weight Loss Versus Temperature for Pine Wood Waste 91
Pyrolysis Oil
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TABLES
No. Page
1 Analysis of Combustion Stack Effluent of 14
Wood Wastes
2 Summary of Results of Run 2 36
3 Operating Conditions 38
4 Overall Mass Balance 43
5 Overall Energy Balance 44
6 Summary of Test Results 45
7 List of Equipment for Portable Pyrolysis System 61
A-l Laboratory Analysis—Run 4 75
A-2 Laboratory Analysis—Run 5 76
A-3 Laboratory Analysis—Run 6 77
A-4 Laboratory Analysis—Run 7 78
A-5 Laboratory Analysis—Run 8 79
A-6 Laboratory Analysis—Run 9 80
A-7 Laboratory Analysis—Run 10 81
A-8 Laboratory Analysis—Run 12 82
A-9 Laboratory Analysis—Run 13 83
A-10 Laboratory Analysis—Run 15 84
A-ll Laboratory Analysis—Run 16 85
A-12 Laboratory Analysis—Run 17 86
vi
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Tables Continued
No. Page
A-13 Laboratory Analysis—Run 18 87
A-14 Laboratory Analysis—Run 19 88
A-15 Trace Element Analyses 89
vii
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FOREWORD
This effort was supported by the Environmental Protection Agency,
Industrial Environmental Research Laboratory, Research Triangle Park
(IERL-RTP), under Contract 68-02-1485. We wish to express our appreciation
to Mr. James Kilgroe and Dr. Max Samfield of IERL-RTP for their many
contributions and suggestions. And a special note of thanks is offered
to Ms. Eleanor Hancock and Ms. Beth Lanier for their invaluable assistance
in the preparation of this document.
It is EPA's policy to report numerical data in metric units. However,
for the convenience of the readers, data reported herein is expressed in
units normally used in U.S. engineering practice. A table for conversion
of these units into the international system of metric units is presented
in Appendix D.
viii
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SECTION I
CONCLUSIONS
From the results of the testing, the following conclusions can be drawn:
The effect on char-oil yields of air/feed is very important;
the lower the air/feed the greater the yields.
Bed depth may have an influence on oil yields but little effect
on char yields. Thus larger bed depth may be desirable to
maximize char-oil yield. (Larger bed depth would also allow
use of a minimum number of air tubes and offers minimum
obstruction to flow and agitator operation.)
The effects of agitation (using the particular agitator geometry
and feed tested) are not significant in influencing char-oil
yields. Agitation would probably allow greater throughputs,
however.
The effect of tube geometry on char-oil yields is apparently
not significant.
The overall mass, energy and chemical balances appear to be
satisfactory; thus giving confidence to the results of the
testing.
From the results of the design study, the following conclusions can be
drawn:
A 200 gon/day (assuming 50 percent moisture) portable system
appears feasible technically, and economically profitable.
The system economics are strongly governed by the fuel price
which can be obtained for the char-oil mixture.
To obtain a maximum economic benefit, the system should operate 24
hours a day, 250 days a year.
Credits for disposal make the system especially profitable but
are not necessary for economic justification.
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Uprating the system capacity would have a large impact on profit.
The travel and down time between operations at separate locations
have only a minor influence on productivity since typical operations
will last two to three weeks.
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SECTION II
RECOMMENDATIONS
The results of this study indicate the desirability of proceeding with
the development of the mobile converter concept. More specifically, a
study of the effects of scale and of using a different feed material is
suggested. Further development work in the utilization of the pyrolysis
gases for operating a modified gasoline engine is also felt desirable.
More work in the area of mechanical agitation should be made. A test
of the burning characteristics of the char-oil mix would be useful.
And finally, the design, fabrication and test of the mobile converter itself
is a necessary step before construction of the complete mobile system
can be accomplished.
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SECTION III
INTRODUCTION
Each year the United States produces hundreds of millions of tons of
agricultural and forestry wastes. These wastes, which represent a serious
disposal problem, also offer a potential source of a perpetually renewable
low sulfur fuel which could be used to help relieve domestic dependence
on foreign oil and gas supplies and thereby reduce our severe balance
of payments problem. Therefore, if a practical technique for converting
even a fraction of these wastes into fuels could be developed, a signi-
cant step toward the solution of our nation's energy shortage would be
accomplished. On a regional basis, the effect of such a development could
be dramatic since there are many areas which would become largely energy
self-sufficient if available wastes could be converted into fuels. In
addition to the obvious advantages, a program for conversion of wastes
into clean fuels could produce an entirely new industry and generate many
new job openings in areas presently depressed both economically and
technically.
Such an energy development program would provide not only an ecologically
desirable method for disposing of wastes and producing fuels, but would
avoid the hazards, such as nuclear accidents and oil spills and the
unsightly blemishes from strip mining, that are associated with other
energy production methods. Because the fuels produced would have a low
sulfur content, they could be burned directly or blended with high sulfur
coals to produce a low sulfur fuel with emissions acceptable to air quality
standards without the need for costly flue gas desulphurization equipment.
There is no doubt that some of the wastes produced are unavailable or
unuseable for such a program. This is because, for example, current
agricultural harvesting equipment often leaves a large amount of crop
residue in the field where it is used as a soil conditioner. While such
wastes could be feasibly collected, there is a question as to the desir-
ability of so doing because of the current high cost of fertilizer and
the wide-spread depletion of the organic content of our soil. However,
much of the wastes are produced at processing plants such as sawmills,
sugar mills, rice mills, peanut shellers, cotton gins, etc., which
because of the availability and the concentrated form of the wastes, are
especially attractive as sources for energy production. It should be
recognized that the recovery potential at these sites is based not only
upon the annually produced wastes but on the accumulated wastes from
many years of prior operation. Indeed, there are canyons filled with
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wood residue in northern California and individual sawdust piles sixty-
feet deep and covering dozens of acres in the Southeast. Therefore,
while the total available agricultural wastes are clearly only a portion
of that produced, the amounts are none the less staggering and the energy
potential is significant in terms of our national energy requirements.
Another concept related to producing energy from wastes is the "energy
plantation" (1 - 2) in which "biomass" would be grown entirely for the
purpose of producing energy. It has been estimated (1) that an area
of less than one third of that involved in farming in the United
States could meet the entire energy requirement of all the installed
electric generating capacity in the country. The nonagricultural area
classified as forest grazing land and grassland ranges, with proper
climate and rainfall suitable for energy plantations, is several times
that area. Therefore the availability of land for energy plantations
is no impediment to its development.
From the above it appears that there is a significant argument that can
be made for the production of energy from "bioconversion," whether the
energy is a by-product or the principal product of agriculture. However,
there are some obvious problems; e.g. :
. Agricultural waste (organic matter) is typically quite wet,'
containing 30 to 70 percent water and therefore relatively
low in heating value per pound.
Since these materials would be scattered all over the country-
side, the transportation costs per Btu to large thermal
conversion plants would be very high.
Because of the water content of these raw materials, the use
of existing thermal conversion equipment is doubtful, at least
at its rated capacity. Most likely new or modified facilities
would be required. (The overall steam side efficiency of boilers
utilizing wet organic fuels such as bagasse and bark, is typically
60 to 65 percent. Thus there is a serious conversion penalty
using these as-received, wet materials.)
The particulate emissions from boilers operating on raw organic
fuels would likely require the installation of expensive flue
gas clean-up equipment.
Agricultural wastes with a few exceptions are produced seasonally,
not continuously. Thus a steady supply of fuel from these wastes
is not available and also it is impractical to tie-up capital
equipment that cannot be used year round.
. Associated with the construction of a waste conversion facility
dependent upon an adjacent, fixed supply of wastes over a long
time period are contractual problems between the producer of the
wastes and the waste utilizer. While initially the waste producer
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may be spending two to five dollars per ton of raw wastes for
disposal, he may hesitate or refuse in a long term contract to
giveaway, or perhaps pay a disposal charge for his wastes. And
clearly, once a facility for waste utilization has been
constructed, the waste producer, upon termination of the original
contract, has the waste utilizer in an uncomfortable economic
position.
The above considerations have limited the development of the concept of
energy production from agricultural wastes in the past, and unless solutions
to the problems described are forthcoming, they will likely curtail future
developments. In reviewing these factors, it should be realized that at
the heart of the operational problem is the high moisture content of the
wastes and the associated high transportation costs. If some means could
be provided to eliminate or minimize these problems, then a major step
would be taken toward the practical development of the concept.
One apparent solution would be to simply dry the wastes before they are
transported; thus avoiding the transportation of all that water. But
the question first arises as to the source of energy required to dry the
wastes. Secondly is the fact that even wet agricultural wastes are
typically quite bulky and drying them will make them even more so.
Therefore while the weight of these materials could be reduced by drying,
their volume would be hardly affected. Thus the transportation cost
benefit would be small or insignificant since the vehicles moving the
wastes would be volume limited. Baling these wastes, or compacting them
somehow to a greater density is a relatively expensive operation, and
not believed to be practical.
Another concept is to utilize a mobile pyrolysis system that could be
transported to the site of the waste production and there convert the
wastes into a char, an oil and a low Btu gas. The gas could be used to
dry the wet feed and to operate the associated equipment and the oil and
char could be mixed together to produce a single dense, free-flowing
solid.* The weight reduction and the associated transportation costs
thereby affected would be very substantial. A further benefit to be
derived is that since the system is portable it would provide greater
leverage for the waste utilizer in contract negotiations with the waste
producer, since the unit could always be moved to a new location. The
portability feature would also guarantee greater equipment utilization
and through proper scheduling between seasonal agricultural wastes and
continuously available forestry wastes could provide an almost constant
supply of fuel.
*Mixing the oil and char is not an essential step but in many circumstances
would be advantageous since it would remove the necessity for a second
materials handling system.
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Finally, since the portable system could be assembled in factories, using
mass production techniques it would likely be less expensive than a
comparable fixed installation.
Therefore it appears that the concept of a mobile pyrolysis system has
merit, but there are still practical problems associated with operating
such a unit in the rural environment. For example, most pyrolysis units
emphasize the production of gas, not char and oil; clearly there is
little practical use for an intermittantly available low Btu gas out in
the countryside. Many pyrolysis units also require expensive front end
systems or elaborate auxiliary equipment. And finally most pyrolysis
systems operate at elevated temperatures, require expensive insulating
materials,and are not easily moved.
The Engineering Experiment Station (EES) at Georgia Tech over the last
eight years has developed a simple, steady-flow, low temperature,
partial oxidation pyrolysis system which is completely self-sustaining.
In the EES design the pyrolysis occurs in a vertical porous bed. A
schematic of this unit is shown in Figure 1. From the figure its operating
features can be seen. This unit requires no special front end system, has
very few moving parts, and depends upon a relatively small blower to
provide the air supply necessary to maintain the partial oxidization of
the feed. The system typically converts a pound of dry organic wastes
into about a half pound of oil and char and one quarter pound of water
and one half pound of gas (allowing for the process air itself).
Typically a ton of as-received wastes would be converted, using the EES
process, to about 450 pounds of a powdered fuel, similar to coal, with
a heating value of 11,000-13,000 Btu/lb. Thus, depending upon the feed
moisture content, the energy available for use at the central thermal
conversion plant could be 75 to 80 percent of that theoretically available
from the original dry waste; and, using a boiler conversion efficiency of
80 to 85 percent, the overall steam-side efficiency of the process could be
65 to 70 percent. Hence the percent of useable energy could be as large as
and perhaps larger than that available with direct burning but with
avoidance or significant reduction of the problems of:
Transporting the wastes.
. Modification or construction of new facilities compatible with
fuels derived from organic wastes.
Emissions resulting from unburned fuel particles.
The powdered char-oil fuel could be burned in either suspension fired
or in stoker fired boilers with esentially no modification. It could
be blended with cheaper high sulfur coal to produce an additional economic
advantage. The EES system thus appears to have many features desirable
for a portable unit.
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Non-Condensible
Gas & Steaa
Pyrolysis
Oil
Waste Feed
(V. N .
Decomposing I J
C. vJJas^te '
^ j ^
-\7—V
\
Process Air
A 7\ TV
"1
Char
Figure 1
EES Waste Converter Schematic
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This report then describes a program directed toward the development
of a portable pyrolysis system for conversion of organic wastes into
clean fuels using the EES waste converter design. The program has two
main objectives which are:
1. "to conduct a parametric study of pyrolytic waste converter
performance as a function of system parameters such as feed
flow rate, bed depth, air flow rate and air tube location.
The purpose of the tests is to optimize the production of
char and oil and minimize the production of gas, and to
obtain data for integrating the pyrolysis sections with other
sections of a portable system.
2. Using the test data obtained, to perform a preliminary design
of a transportable agricultural waste conversion system having
a nominal feed rate of 200 tons/day, assuming 50 percent
moisture."
The report is divided broadly into two sections describing the test
program and the design study. However, a brief description of previous
EES work in pyrolysis is also presented to put the results of the study
in a wider perspective.
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SECTION IV
EES EXPERIENCE IN PYROLYSIS
GENERAL
The involvement of the EES in the area of conversion of solid wastes by
pyrolysis began with work eight years ago to develop a means to dispose
of peanut hulls without producing the pollution problems associated with
incineration.
The first pilot plant system, approximately five feet tall, was designed
to reduce peanut hulls to a char and a combustible gas. The system built
in 1968 was operated on a batch basis at first and then on a continuous
basis with a manual input feed. Hundreds of pounds of peanut hulls were
converted to char and off-gases during several months of testing with
this equipment. Enough data were obtained to demonstrate the feasibility
of developing an automated prototype converter with the vertical, porous
bed design.
The large prototype, constructed in 1971 and shown in Figure 2,was built
to operate continuously at an input feed rate of 4,000 pounds per hour.
The unit was approximately 11 feet in height, and the reaction chamber
was mounted on top of a water-cooled collection chamber. The feed-out
was accomplished by a horizontal screw at the base of the chamber. The
off-gases were treated as potentially explosive in these tests, and
consequently, a system was constructed to burn the gases in an unconfined,
diffusion controlled flame. Experience with these gases showed that they
could be burned easily and safely by premixing and igniting in a conven-
tional fashion. This system was operated over a period of many months,
while processing thousands of pounds of feed. The reaction chamber of
this converter was designed to have a minimum weight and only enough
operating life to demonstrate the automatic operation of the process.
This was done to reduce the overall cost of this experimental prototype.
Consequently, the test program started with low temperature operation
and on succeeding tests the temperature was raised. The internal structure
of the reaction chamber eventually failed after approximately six months
10
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Figure 2. First Generation EES Pyroltic Converter,
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of testing as a result of the elevated temperature.
Based on the data and results from the first pilot plant unit and the
experimental prototype, an improved pilot plant unit, used in the
present study and described in Section V, was designed and built. In
addition a large 50 dry ton/day demonstration plant was built by the
Tech-Air Corporation, 2231 Perimeter Park, Atlanta, Georgia, who is the
licensee for the EES process.
The demonstration plant is located in a wood yard in Cordele, Georgia,
and operates on wastes from the sawmill. This system has been in
successful operation now for more than three years and was field tested
for two years prior to that. The char produced is sold, the pyrolytic
oil produced is used in an oil-fired kiln drier, a portion of the gas
is used to dry the feed and the remaining gas is flared. Plans are
to construct a process steam boiler which will utilize the remaining
gases. The system is pictured in Figures 3 and 4. An idea of scale
can be obtained by noting the control shed in the lower right hand
corner of the overall view, Figure 3. A drier which utilizes hot
combustion gases from the off-gas burner reduces the water content
of the initially wet wastes down to four percent. The input feed material
varies in moisture content from 20 to 55 percent, depending on weather
conditions, season of year, and the amount of sawdust in the feed.
Another attractive feature of this system is the cleanliness of its
exhaust which is completely invisible to the eye. A recent analysis of
the combustion stack gases was made and the results are presented in
Table 1. These uncontrolled emissions are lower than existing federal
and state standards for incinerators.
Recently, a new, larger (one ton/hour) more sophisticated pilot plant,
with improved instrumentation, and located near the smaller EES pilot
plant, has been constructed. This system is primarily designed to
investigate in greater detail the parameters of the pyrolysis process at
a larger scale than previously possible. A photograph of this system
is shown in Figure 5.
EXPERIMENTAL WORK
The EES work has involved both laboratory bench scale and pilot plant scale
studies of pyrolysis. In both of these complementary efforts, a wide
variety of waste materials have been studied.
Laboratory Bench Scale Pyrolysis Experiments
These tests have been made to determine the general feasibility of a
particular feed for pyrolysis, to analyze the products, and to determine
12
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Figure 3. Wood Wastes Field Demonstration Unit-
Overall View.
Figure 4. Wood Wastes Field Demonstration Unit-
Char Handling and Storage System.
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Table 1
Analysis of Combustion Stack
Effluent of Wood Wastes
Component
Water
Oxygen
Nitrogen
Carbon Dioxide
Carbon Monoxide
Particulates
A.
Composition
by Volume
14%
9.0%
69%
7.7%
30 ppm
14 micro
gms/f t^
COMPONENTS DETECTED
Test Method
Liquid Impinger collection
GCTC1
GCTC
GCTC
MSA2
Liquid Impinger collection
Mass Rate of
Pollutants
(pounds/minute)
NA7
NA
NA
NA
6.5 x 10~2
9 x 10~4
COMPONENTS TESTED FOR BUT NOT DETECTED
Threshold Sensitivity
Component
Hydrogen
Methane
Sulfur Dioxide
Nitrogen Dioxide
Ammonia
Hydrogen Sulfide
of Tests6
(ppm)
0.0009
0.0009
0.4
0.04
0.09
0.009
Test Method
GCTC
GCFID3
MSA4
MSA5
Odor
Odor
Gas chromatography—thermal conductivity detector
MSA—Mine Safety Appliance Co. Test Part No. 91229
Gas chromatography—Flame ionization detector
A
MSA—Mine Safety Appliance Co. Test Part No. 92623
MSA—Mine Safety Appliance Co. Test Part No. 83099
These components would have to be present in concentration shown to be
detected; therefore, these results represent the maximum amounts of these
components which could be in the stack gas
7NA—Not Applicable
14
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Figure 5. New EES Pyrolytic Converter,
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the theoretical yields available. The general technique employed for the
pyrolysis of a particular material is as follows: the material to be
pyrolyzed is placed in the metal pyrolysis tube either two inches I.D. or
six inches I.D. (see Figure 6). The ends are capped, and the closed
unit is placed in the appropriate Lindberg tube furnace. The downstream
end of the metal tube is connected to a condensation train as shown in
Figure 7. The material in the tube is heated to, and held at, the desired
temperature for a predetermined time. Spacers inside the pyrolysis
tube confine the charge to a uniformly heated zone in the furnace.
Internal temperatures are monitored with thermocouples.
The condensation train is arranged so that the high-boiling condensate
is collected mainly in one trap, while the water and low-boiling organic
material is collected in another trap. The non-condensible gases, after
passage through a glass-wool scrubber and a cold trap, are measured with
a wet test meter and then collected in a large plastic bag for subsequent
analysis by gas chromatography.
On completion of a pyrolysis experiment, the exit from the pyrolysis tube
is closed to prevent air from entering the tube and reacting with the hot
char while the system cools. After cooling, the system is disassembled,
and the char is collected, dried, and weighed. The organic material and
water from the condensation train is collected and stored for further
analysis. The gas sample is analyzed immediately after collection by
use of various gas chromatographic columns and techniques to determine
the composition. The pyrolytic gases are predominantly hydrogen, carbon
monoxide, carbon dioxide, methane and lesser amounts of gaseous hydro-
carbons. The analyses on the char include total ash, acid insoluble ash,
elemental composition, volatiles, heating value, and density. The con-
densible organic material is usually characterized by a determination of
percent water, heating value, and elemental composition. Pyrolysis
studies have been made with a variety of different materials including
pine bark, pine sawdust, mixtures of pine bark and sawdust, cotton gin
waste, bagasse, hardwood bark, hardwood chips, peanut shells, carpet
waste, nonmetallic automobile waste, municipal waste, dried sewage sludge,
and dried chicken manure.
To illustrate the type of results which were obtained from these laboratory
experiments, normalized yields (pounds of pyrolytic product per pound of
feed) for a mixture of pine sawdust and pine bark are plotted in Figure
8 as a function of temperature. The figure shows that the char yields
decrease with increasing temperature, and this can be attributed to the
fact that the volatile content of the char decreases as the operating
temperature is increased. The non-condensible gases increase with
increasing temperature and begins to show a leveling-off at the higher
temperatures. This increase can be attributed to the formation of
condensible oil from the volatiles liberated from the char as the temper-
ature increases. The aqueous yield decreases with increasing temperature.
16
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Figure 6. Pyrolysis Tube Furnace for Bench Scale Experiments
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LEGEND
1. Pyrolysis tube
2. Heated condenser
3. Heated scrubber
4. Heated trap
5. Ice bath
Water cooled condenser
Water cooled scrubber
Chilled trap
Glass wool scrubber
Dry Ice trap
Siphon breaker
Wet test meter
to gas
collection
bag
Figure 7. Condensation Train for Pyrolysis Experiments
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!i
i
8
I
s
0.40-
0.35
0.30
6.25
0.20
0.15
400
Char
I
600
I
800
I
1000 1200
Pyrolysis Temperature *F
Condensible
Organic
Material (Oil)
Non-Condensible
Gas
Aqueous
1400
Figure 8. Mass Balance for Pyrolysis of Pine Sawdust and Bark
19
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As the temperature increases, the formation of water is evidently a less
dominant reaction while the reaction leading to the formation of more gases
and oil became more important. These data are useful in predicting the
effects of temperature on yields in pilot plant experimental work.
The heat available from the pyrolysis of pine sawdust-pine bark mixture
is presented in Figure 9. The significant information to be obtained
from this graph is that the sum of the heat values at each pyrolysis
temperature is very close to the heat value of the dry input feed material.
These data show that the total heat content of the input material over a
fairly wide temperature range can be accounted for in the pyrolytic
products (the external heat required to pyrolyze the feed being negligible).
Also shown in Figure 9 is a plot of the ratio of the energy available in
a mixture of the char and oil to the total energy in the wood waste. It
appears that to recover the maximum energy in the char-oil mixuture the
pyrolysis should be conducted at as low a temperature as practical.
Pilot Plant Pyrolysis Experimental Work
The overall objective of the previous pilot plant experimental work has
been to determine the operating characteristics and parameters with
specific materials. One important question that has been answered with
each material is how well the material feeds through the pyrolytic
converter. Many materials are dense enough and are of such a physical
shape and size that they are essentially free-flowing and feed easily
through the converter. Some examples are macadamia nut shells, hardwood
chips, and pine sawdust. Pine bark must be hogged before it is suitable
as a feed material. Peanut hulls, on occasions, have bridged in the
converter and hence some agitation is needed to break the bridge. Other
materials, such as bagasse, nonmetallic automobile waste, and cotton gin
waste present some problems with feeding. With cotton gin waste, for
example, it has been found necessary to use mechanical agitation in the
converter to keep the material from bridging in the pyrolysis zone.
The testing has indicated that the moisture content of the feed material
should be less than 10 percent. If the moisture content is in the range
of 35 to 50 percent, as is the case with pine bark and sawdust, then the
material must be predried. Other data and information obtained from
pilot plant pyrolysis experiments include throughput feed rates, yields of
char and condensible organic material, and composition of non-condensible
off-gases. Ratios of process air to feed material rates are obtained
and correlated with yields and quality of products. Materials that have
been processed in the EES pilot waste converter include peanut hulls, pine
bark, pine sawdust, mixtures of pine bark and sawdust, macadamia nut shells,
nonmetallic automobile waste, hardwood chips, cotton gin waste, and
municipal garbage.
In summary, the EES pyrolysis work conducted prior to this study has
indicated that there may be material handling problems associated with
20
-------
9000-
ii
8000-
6000-
5000-
3000-1
I .
2000-
1000-
400
0 measured heating value
Sum of Heats
Percent
Available Energy
in Char and Oil
Condensible
Organic
Material (Oil)
_ 100
-90
-80
Latent Heat
of Oil
-70
_60
Non-Condensible
Gas
-50
Sensible Heat
Latent Heat
of Aqueous
I
600
\ \ I
800 1000 1200
PYROLYSIS TEMPERATURE °F
I
1400
160C
?
0)
w
cr
M
It
l-t
Figure 9. Heat Available from Pyrolysis of Pine Sawdust and Bark
21
-------
bulky wastes, in which case some form of mechanical agitation may be
required. Further, it appears that the pyrolysis temperature has a
significant effect on product yields. Since the bed temperature is
controlled by the air/feed ratio, it follows that in the pilot plant
work this latter ratio should have a major influence on the system
output.
22
-------
SECTION V
TESTING
The object of the testing in the current study was primarily to determine
the optimum operating conditions for maximum production of char and oil
and for minimum production of gas using the EES pyrolysis system. With
this in mind, the test instrumentation, the test operation and the selection
of the test parameters were made, within practical limits, to shed as much
light as possible on those conditions most favorable for application to
the portable converter concept. The primary test parameters were: the
air/feed ratio, the depth of the porous bed, the geometry and number of
air tubes, and the use of mechanical agitation. A total of 19 runs were
made. This included an initial shakedown run, a test run of the effects
on production rates and yields of changing the feed from a fifty-fifty
mixture of bark and sawdust to pure sawdust, three aborted runs, and
fourteen successful runs.
In the following sections a description of the facilities utilized, the
test and calibration procedure, the laboratory procedure and the results
of the testing are presented.
FACILITIES
The testing was conducted in the six ton/day EES pilot plant. A process
flow diagram of the pilot plant is shown schematically in Figure 10.
Photographs of the unit showing views of the separate components involved
are presented in Figures 11 through 16.
The system operates as follows: the wet sawdust is first dried in a propane
fueled crop drier, then weighed and stored in drums. During a test the
drums are emptied into a receiving bin and from there the feed passes onto
a conveyor which transports it to the pyrolysis unit. The pyrolysis unit
is 10 feet tall and is four feet on each side. The average inside
dimensions of the bed are two feet by two feet and it is four feet deep.
The feed enters the converter through a gate valve and passes down through
the vertical bed. Process air tubes are located in the lower portion of
the bed. These water cooled tubes supply enough air to oxidize the feed
in their immediate vicinity and thereby produce sufficient heat for
pyrolysis of the remaining bed material. The char at the bottom of the
23
-------
Wet
Sawdust
Dryer
Hot Water
to Dump
Cold Water.
Air
Compressor
) Orifice
_f (—Cyclone
JL-j >Cooling
, Fan
Hot Gas to
Atmosphere
Converter
r
Hot Gas
•Jaste
Particles
r A
Condenser
Charcoal
Oil
Totalizing
Flow Meter
r-Orifice
S~\ Warm
O{
V __ x
Sample port
Burner
—-Blower
Air
EES Pyrolytic Unit Process Flow Diagram
Figure 10
-------
Figure 11.
EES Pyrolytlc
Converter—
Feed Bin and
Feed Conveyor.
Figure 12.
EES Pyrolytic
Converter—
Close-up of
Feed System.
Figure 13
EES Pyrolytic
Converter—
View of Con-
denser Train and
Afterburner.
-------
Figure 14. EES Pyrolytic Converter—
Close-up of Condenser Train
and Afterburner showing
Particulate Material
Separator.
Figure 15. EES Pyrolytic Converter-
Close-up of Unit.
Figure 16. EES Pyrolytic Converter-
Feed System Showing
Pneumatic Valve.
26
-------
bed passes into a screw conveyer that transports it to a valve assembly
where it is emptied into receiving drums.
The gases produced during decomposition of the feed pass upward through
the downward moving feed and leave the unit near its top. The gases
then pass through a cyclone where particulates are removed and then
to an air cooled condenser which operates at a temperature above the dew
point of the mixture. The condenser removes the higher boiling point
oils which are collected and weighed. The remainder of the uncondensed
oils, the water vapor and the non-condensible gases pass into a vortex
burner which incinerates the mixture.
The instrumentation utilized in the study includes:
1. an in situ calibrated orifice to measure process air flow rate
2. an in situ calibrated orifice to measure off-gas flow rate
3. scales used to weigh the dry input feed, the char, and the oil
yields
4. a water meter to measure total cooling water flow
5. dial thermometers to measure inlet and exit cooling water
temperatures
6. various thermocouples to measure: pyrolysis gas temperatures
at several points in the system, internal bed temperatures,
external surface temperatures and the vortex burner temperatures
7. a multiple channel recorder to provide continuous data as to
various thermocouple outputs
8. a gas sampling system for laboratory analysis of the off-gas
composition
The system operates at a pressure of a few inches of water above ambient.
Thus there is some gas lost when the inlet feed gate valve operates. As
the process rate of the unit increases, the gas production increases and
the pressure consequently rises. The unit has pressure relief doors
which operate at about 10-12 inches of water. These doors place an upper
limit to the allowable processing rate and provide a safe means of
relieving overpressures for any system malfunction.
The process rate of the system is governed by the rotational speed of the
;char output mechanism. A level indicator senses the need for additional
feed and activates the gate valve and conveyor system to provide the
necessary input. Thus, the gate valve cycles only upon demand, not
continuously; hence the gases lost through* this valve do not represent a
significant energy loss or pollution problem.
"27
-------
The condenser is of a relatively simple design having a series of air
cooled vertical tubes through which the hot pyrolysis gases pass. It
has been observed that oil droplets are frequently stripped off the inner
tube walls by the fast moving gases and carried in suspension through
the off-gas system, past the off-gas flow orifice and into the burner.
This results in some loss of oil; however, data analysis techniques are
used to account for this loss.
In several of the tests a mechanical agitation system was utilized to
enhance the flow of material through the waste converter and to prevent
the formation of bridges or arches which can obstruct the downward
moving feed. A schematic view of the agitator used in these tests is
shown in Figure 17. The system was constructed of heavy walled steel
tubing and was water cooled. It was powered by an automatic piston-
cylinder system which provided a continuous reciprocating motion. A
helical cam provided approximately 150 degree rotation of the agitator
on each forward and reverse stroke.
CALIBRATION AND TEST PROCEDURE
Prior to the testing many elements of the system instrumentation were
carefully calibrated. The accuracy of some components such as the
thermocouples, however, was not checked since the required precision did
not demand temperature measurements of greater accuracy than the nominal
values of the manufactured wire. Also the accuracy of the cooling water
meter was taken at face value from the name-plate data. However, care-
ful attention was given to calibrating the process air orifice and also
the off-gas orifice against a known reference laminar flow element.
Both these ASME sharp-edged orifices were calibrated in situ to insure
accuracy. An input feed rate back-up system, which measured the number
of rotations of a screw in the receiving bin, was calibrated directly by
weighing a number of drums of feed passing through the bin. (This was
later used as a check to be certain that all input drums were recorded
properly.) Tares were individually determined for all the drums in
which the dried feed was stored.
The procedure during the tests was relatively straightforward: the unit
loaded with feed or char the previous day, was heated-up by use of an
external gas fired burner. When the temperature was sufficiently elevated,
the process air was introduced slowly and the burner turned off. Normally
the bed temperature would begin to rise sharply after introduction of
the process air; however, if the air was added too soon, erratic operation
occurred and it was necessary to turn the gas fired burner on again for
additional heat. Once it was apparent that the system was operating in
a self-sustaining mode, the output system was activated and slowly brought-
up to the operating capacity chosen for the test. Likewise the process
air feed rate was adjusted to correspond to the desired ratio of air-to-feed
for the test. The system was then allowed to come to a steady-state
condition, which required a nominal four hours. Constant checks and
adjustments were made during this period to insure that the actual
operating conditions were those desired; however, it was found that the
28
-------
Figure 17
-SCHEMATIC OF AGITATOR
Off Cu
Oi«r Output
29
-------
ability to establish a given feed process rate and a given air-to-feed
ratio was limited to a tolerance of plus or minus about 10 percent.
Upon initiation of the test run, continuous records of time, feed input,
char output, oil output, orifice manometer readings, and the various
temperatures were made. In addition a continuous sample of the pyrolysis
off-gases was taken. Every effort was made to insure that the unit
remained in a steady-state operating mode by continuous surveillance and
adjustment of the various instruments measuring and controlling the inputs
of the system. "Grab samples" of the feed from each drum were taken
throughout the run. Each run lasted four hours. At its completion all
of the char and oil produced were collected and representative samples
of each were obtained. The char sample was obtained by sequential use
of a riffle splitter to cut the total char yield down to, typically, a
five pound specimen. The oil which was collected in a 55 gallon drum was
mixed thoroughly and a sample of about one pint was taken. All of the
feed grab samples were mixed and cut using the riffle splitter to obtain
a composite sample of about five pounds.
LABORATORY PROCEDURE
The laboratory played a vital role in the determination of the feed and
products characteristics and in the subsequent analysis of the data. Thus
the work was checked carefully and every precaution made to insure the
accuracy of the results. However, despite these efforts there are
occasional instances where inconsistencies did arise. While inherent
errors associated with the specific test procedures themselves clearly
contributed to the problem, it is believed that the principal explanation
for these occasional inconsistancies lies in the difficulty of sampling.
Frequently and of necessity a few grams sampled from a run were taken to
represent the entire production of the oil or char in some piece of
sensitive, chemical analysis laboratory equipment. Thus even though
duplicate tests were usually made, there are some occasional problems
with repeatibility of results. While inspection of the data reveals that
these variations are predominantly less than one percent and that the
overwhelming impression is of good repeatability, the presence, especially
in the elemental carbon, hydrogen, nitrogen and oxygen (CHNO) analysis,
of even small inconsistancies in oxygen content was found to have a
significant effect on the test results. Thus, while these data, by
ordinary standards, stand up well, the sensitivity of the overall test
results to some of these data make close scrutiny necessary.
It might be noted that conventional practice in coal analysis involves
obtaining oxygen percentage by difference, once the CHN analysis is complete.
This is apparently done because the oxygen percentage must be obtained
from analysis of a separate sample, while the C, H, and N analyses are
made with a single sample. In the tests reported, the oxygen was measured
separately, but because of the sampling difficulties mentioned, there are
occasional inconsistencies and caution should be exercised in the casual
use of these numbers. Clearly, the calculation of oxygen content by
differences is a respectable alternative.
3
-------
A review of the breadth of the laboratory work done reveals a wide
assortment of different analytical procedures. These procedures include
analysis of the:
1. Feed for:
percent moisture
percent ash
. percent acid-insoluble ash
percent carbon
. percent hydrogen
percent nitrogen
percent oxygen
heating value
2. Char for:
percent moisture
percent ash
percent acid-insoluble ash
percent volatiles
percent carbon
percent hydrogen
percent nitrogen
percent oxygen
heating value
3. Oils for:
percent moisture
. percent carbon
percent hydrogen
. percent nitrogen
percent oxygen
The composition of the off-gas was determined by gas chromatography and
reported as:
percent nitrogen
. percent carbon monoxide
percent carbon dioxide
percent hydrogen
percent methane
. percent C? components
percent C components
percent C. components
jIn addition to the above, analysis of selected samples of feed, char and
joil were made to determine the quantities of trace elements such as:
31
-------
zinc
copper
colbalt
nickel
iron
vanadium
chromium
manganuse
sulfur
chlorine
The laboratory also provided data regarding the oil viscosity over a
range of boiling points. And finally, analysis of the stack gas
emissions for a selected test was made. Presented in the following
sections are brief descriptions of the laboratory procedures followed
to obtain all these data and estimates of the accuracy limits intrinsic
to the tests themselves. The data itself is presented in Appendix A.
Solid Samples
Sample Preparation - The solid samples examined consisted of the dried
pine sawdust used as feed material for the waste converter and chars
produced by the convertor. The sample size received in the laboratory
ranged from one to eight liters for the sawdust feeds and from one to
two liters for the char products.
The samples were thoroughly mixed and divided by quartering or by a
riffle splitter to produce a representative one liter sample, which
was passed through a Wiley Model 4 mill using a six millimeter screen.
The ground sample was again mixed and divided into approximately equal
parts. One part was again passed through the Model 4 Wiley mill using a
two millimeter screen. This material was then mixed and reduced by
quartering to approximately 100 grams. The 100 gram sample was then
passed through a Wiley intermediate mill using a 40 mesh screen, remixed,
and quartered. The larger portion of the -40 mesh sample was stored
in a tightly closed glass bottle for use in laboratory analysis. The
remaining quarter of the material was again passed through the Wiley
Intermediate mill using an 80 mesh screen, remixed, and stored in a
tightly capped vial for elemental analysis.
Analytical Procedures - 1. Percent Moisture in Sawdust Feeds: Duplicate
1.000 gram samples were placed in aluminum dishes and dried for one hour
at 105°F in a forced air oven. The dried samples were cooled in a
desiccator and weighed. The estimated error is + 0.6 percent (absolute).
2. Percent Moisture and Percent Volatiles in Chars: These analyses
were performed by ASTM Method D-271. The estimated error is + 0.3 percent
(absolute).
3. Percent Ash and Percent Acid-Insoluble Ash in Feeds and Chars:
Duplicate 1.000 gram samples of the feed or char were weighed into tared
32
-------
porcelain crucibles, ignited to constant weight in a muffle furnace at
600°C, cooled in a desiccator, and reweighed. The ash was digested in
a 1:3 mixture of hydrochloric and nitric acids for 30 minutes. The
mixture was then diluted to approximately 100 ml. and filtered through
a Whatman No. 40 paper. After thorough washing with distilled water
the filter paper and undissolved ash was returned to the crucible used
for the original ash determinations, ignited to constant weight at 600°C
cooled in a desiccator, and weighed. The estimated error is + 0.2
percent (absolute). ~~
4. Heating Values: The heating values of the feeds and chars
were determined in a Parr Plain (Isothermal Jacket) oxygen bomb calorimeter,
following the procedures described in pp. 33-38 of Oxygen Bomb
Calorimeter and Combustion Methods, Technical Manual No. 130, Parr
Instrument Company, Moline Illinois (1960). Agreement among replicate
samples was better than 2.5 percent (absolute) for the feeds and 3.5
percent (absolute) for the chars.
5. Elemental Analysis: Carbon, hydrogen, nitrogen, and oxygen
were determined using a Perkin Elmer Model 240 Elemental Analyzer. The
manufacturer claims a precision of + one percent (relative) for pure,
crystalline materials. Because of the heterogeneous nature of the .
samples, and the resulting difficulty of selecting a representative
three milligram sample, and due to loss of volatiles from the chars in
the purge fraction of the analytical cycle, occasional variations as
high as 12 percent (absolute) have been observed in the carbon and
oxygen determination on char samples. In most cases, however, the
agreement was better than six percent (absolute) for carbon and oxygen
in the feeds and chars. Agreement among replicate hydrogen or nitrogen
determinations was better than one percent.
6. Trace Metals Analysis: Five gram samples of sawdust feeds and
chars were ashed at 600°C and the ash was digested in aqua regia. The
mixture was diluted and filtered through glass filter paper, which was
then washed with distilled water. The filtrate and washings were combined
and diluted to a known volume in a volumetric flask. Trace metals were
determined on an Instrument Laboratories Model 251 Atomic Absorption/Flame
Emission Spectrophotometer, according to the Instrumentations Laboratories
Manual. Copper, chromium, cobalt, iron, manganese, nickel, and zinc were
determined by atomic absorption. Vanadium was determined by flame emission.
The occasional high level vanadiums were rechecked on separately ashed
samples. Since the rises in vanadium levels were accompanied by rises in
the levels of iron and manganese it was believed that the relatively high
level of metals arose from tool steel introduced during materials preparation
or sample grinding.
Oil Samples
Sample Preparation - The oil samples received in the laboratory were
stored in tightly closed glass bottles and stirred before each analysis.
33
-------
Analytical Procedures - Percent Moisture in Oil: The percent moisture
in the oil was determined by the method of Dean and Stark. The error
is believed to be + five percent (relative), although the oil is known
to begin to decompose partially with liberation of additional water at
the temperature of the toluene-water azeotrope, and that acetone and
other water soluble compounds have been detected in the head space over
stored oil samples.
Non-Condensible Gas Samples
Sample Preparation - Gas samples were drawn continuously from the head
space in the waste converter or from the upstream end of the condensers.
The sample stream was passed through a series of water cooled condensers,
a glass wool demister, an ice cooled trap, a chemical drying tube, and
a dry test meter to a tee in the sampling line. From the tee the major
portion of the sample was exhausted to the atmosphere through a vane
type pump. A smaller portion of the stream was led from the tee through
a tubing pump and a wet test meter into a 96 liter "Saran" gas collection
bag. The flow rate in the gas streams was held constant throughout the
sampling periods. At the end of the test the waters and oils from the
condenser train were measured and the gas collection bag was closed and
returned to the laboratory for analysis.
Analysis of Non-Condensible Gas Samples - The gases were mixed by kneading
the sample collection bag and their concentrations were determined by
gas chromatography. Oxygen and nitrogen were determined using a Perkin
Elmer Model 990 Gas Chromatograph using helium carrier gas, a Molecular
Sieve 5A column, and a thermal conductivity detector. Hydrogen was
determined in a similar manner using argon as the carrier gas. Carbon
monoxide, methane, and carbon dioxide were determined in the same
instrument using helium carrier gas and an activated carbon column.
Hydrocarbons containing two or more carbon atoms were determined in a
Perkin Elmer Model 154 instrument using helium carrier gas, a Perkin
Elmer "R" column, and a flame ionization detector. The estimated error
was + five percent (relative).
Stack Gas Analysis - Gases were drawn from the exit of the vortex burner
through a stainless steel probe then through a "Tygon" connecting tube
into a glass gas collection bottle equipped with a rubber septum and
glass stopcocks. After thoroughly purging the bottle with stack gases,
the bottle was closed and returned to the laboratory for analysis by
gas chromatography, as described in the preceding section.
RESULTS OF EXPERIMENTAL PROGRAM
General
The importance to the conduct of the tests of rapid-feed-back of the
laboratory results was one of the major lessons learned from the test
34
-------
program. Without the rapid turn-around of the data, the testing would
have been practically conducted in an information vacuum. Thus it was
essential that the overall test results be computed as they were
generated to maximize the useful information from the experimental
work. Hence while in this study it was not always possible to get
written laboratory results in the time desired, continuous verbal
communication with the laboratory personnel provided sufficient
information to adequately guide the testing.
In the testing, a total of 19 runs were made, however the data for only
14 are presented in detail here. These are runs 4, 5, 6, 7, 8, 9, 10,
12, 13, 15, 16, 17, 18, and 19. The detailed results from runs 1, 2, 3,
11, and 14 are not reported for the following reasons:
Run 1 was basically a shakedown to check out newly installed
instrumentation and modified test procedures.
Run 2 was only a preliminary test and conducted to determine
the difference in the char and oil yields between operation
with feeds of pure sawdust and a fifty-fifty mixture of sawdust
and pulverized bark. In the run, separate two hour tests were
made at a constant feed rate and air/feed ratio. Table 2
presents the test conditions and the results of this run.
From this table it appears that the yields are essentially
equivalent and for this reason and because a local convenient
supply of pulverized bark was not available, all further
testing was conducted using sawdust alone.
Run 3 was aborted because of a small leak in one of the
cooling water lines.
Run 11 was an attempt to duplicate run 7 but because of an
inability to establish close enough correspondence to the
desired test conditions, it was terminated.
Run 14 was an attempt to test at low air/feed and at a very
low feed rate. The test was terminated because the unit
operation became unstable and the output became intermittant.
One of the parameters to be investigated in the test program was that
of mechanical agitation. The use of agitation has as its objective the
increase in process rate and the prevention of blockages-to-flow which
sometimes can occur with bulky feeds. To evaluate the effects of
agitation on yield, a comparison should be made of the effects on
maximum throughput with and without agitation. This was tried but in
was found that at a certain process rate without agitation the operating
pressure rose to near the maximum allowable. There is little doubt that
had the maximum allowable unit pressure been higher, then greater process
rates would have been possible without the need for agitation. Clearly
with agitation the process rate and pressure would have increased even
further. Thus the limitations of the unit operating pressure prevented
the evaluation of the effects of agitation on maximum process rate.
35
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TABLE 2
SUMMARY OF RESULTS OF RUN 2
Sawdust Sawdust/Bark
Feed Rate (pound/hour) 368 385
Air/Feed (pound/pound) 0.36 0.35
Char (pound) 143 166
Char Yield (percent) 19.4 22.5
"Oil" (pound) 92 93
"Oil" Yield (percent) 12.5 12.1
36
-------
Only the influence on product yields could be tested. Had the unit been
drafted, rather than pressurized, then the draft fan might have been
operated at a higher rpm and the problem avoided. However with sawdust,
which is a relatively free-flowing material with a small angle of
repose, it might be expected that the influence of agitation on process
rate would not be strong in any case and therefore the effects on
maximum process rate would likely be unimportant.
Thus while the original objective to evaluate the effects of agitation
could not be completely met, the other test parameters were studied
with no difficulty and the conduct of the tests, as subsequently
described, was relatively straightforward.
Presented in Table 3 is a summary of the test conditions for the 14
reported runs. The table shows the values of bed depth, air/feed ratio,
feed rate and the number of air tubes utilized. Also indicated is
whether or not the mechanical agitator was operated and also the air
tube configuration investigated. Clearly there are a large number of
tests that could be conducted with even two values of each of these
parameters. With a program of only 14 tests, some discretion had to
be applied in selection of the test conditions. Therefore the choice
of the parameters used in the tests was substantially influenced by
experience from previous tests and when a parameter was seen to have
little effect on the results, further investigation of its influence
was abandoned.
In considering the test parameters, it was anticipated at the outset
that the most desirable results were to be obtained at low air/feed
ratios (since this corresponds to low temperatures) and at maximum
bed depth. Therefore the amount of testing at the greatest depth
given equalled all that at the two lower levels combined, with the
minimum depth given least. It was also anticipated that with sawdust
the effects of agitation would be unimportant on yields; therefore
these tests were performed early in the program, verifying the expected
results. Likewise the effects of air tube geometry and the number of
air tubes was not expected to be significant, so only a few tests at an
intermediate bed depth where the tube geometry could be varied easily
were made.
Therefore in the test program emphasis was placed on the effects of
air/feed ratio and feed rate on the product yields at a maximum bed
depth. In the tests at maximum bed depth the practical operating limits
of the unit at minimum and maximum process rates and at minimum air/feed
ratios were also investigated. Because these limits were reached in
runs 6 and 13 and because the existence of these limits influenced the
oil yields, especially, care must be exercised interpreting the results
from these two runs. Otherwise the data from the runs at the greatest
bed depth appear consistent with the general trends of the overall test
results.
37
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TABLE 3
Operating Conditions
lun
lumber
4
5
9
10
17
18
19
6
7
8
12
13
15
16
Bed
Depth
(in.)
18
18
27
27
27
27
27
39
39
39
39
39
39
39
Number
Agitation Air Tubes-
no 4
yes 4
no 3
yes 3
no 3
no 2
no 2
no 2
yes 2
no 2
no 2
no 2
no 2
no 2
Air Tube*
Configuration
A
A
B
B
B
C
C
D
D
D
D
D
D
D
Air/Feed
(Ib/lb)
.47
.53
.70
.64
.38
.58
.42
.27
.56
.35
.45
.38
.22
.49
Feed/Rate
(Ib/hr)
291
246
184
184
195
189
186
491
202
226
237
118
346
222
* Configuration A involved four tubes, 2 at a depth of 16 inches, and
two at a depth of 20 inches.
Configuration B involved 3 tubes at a depth of 27 inches.
Configuration C involved 2 tubes at a depth of 27 inches.
Configuration D involved 2 tubes at a depth of 39 inches.
38
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Data Analysis
Before discussing the results of the runs specifically, the procedure
used to analyze the raw data should be described. The raw data comprised
the basic information concerning feeds, temperatures, product yields,
etc. from the tests; but the feed, the oil and the off-gases contained
water, for example, which had to be accounted for. Therefore, the
laboratory analysis of these samples was used to correct the data to a
dry basis. Hence for this reason and for others there was a continuous
interplay in the data reduction between the laboratory results and the
basic test results. Moreover, in the reduction of the data and the
computation of the mass and energy balances, additional chemical balances
were made to complement and correct the basic relationships. The
following is offered to illustrate why this was necessary:
Throughout the test program it was observed on numerous
occasions that oil was collecting in and dripping from a
flange upstream of the burner but downstream of the condenser
and the off-gas flow orifice. This oil was apparently passing
through the orifice in the form of droplets and had its origin
in the condenser where it was picked up by the off-gas stream.
Several efforts to prevent this from occurring proved futile
and it was finally concluded that the design of the condenser
itself was primarily the cause. Because of this.occurrence
the basic orifice measurements were considered suspect and,
the use of a nitrogen balance was employed to determine the
off-gas flows. Moreover because of the loss of oils, the
resulting oil yields were significantly lower than anticipated
from the laboratory results but again a back-up technique, a
carbon balance, allowed an estimate of the amounts lost to be
made. In terms of the total feed flow rate, the amount of oil
passing through the orifice did not represent a significant
mass loss, however in terms of the energy flow, it represented
a substantial proportion and corrections were necessary to
obtain an adequate energy balance.
Thus in the mass and energy balances, a number of additional chemical
balances and checks were made. To illustrate this procedure, the complete
data reduction process for the various chemical and mass balances is
presented schematically in Figure 18. Study of the figure indicates that
it is divided into two sections, e.g., Inputs and Outputs. Concerning
Inputs, the figure shows that the feed was analyzed for its water content,
and C, H, N and 0 analyses were performed. This then allowed computation
of the amounts of dry feed processed and the corresponding amounts of
water, carbon, hydrogen, nitrogen, and oxygen. The process air flow
rate and the chemical composition of atmospheric air allowed calculation
of the amounts of nitrogen and oxygen utilized.
The output char contained a small volatile or moisture content and this
was determined in the laboratory along with the elemental composition
which was found by use of a CHNO analysis. These procedures allowed
39
-------
rifura 1*
Man and chraleal lalanca Calculation Procedure
OUTPDT
Heamre
Tachnleuea
Laboratory
Determination
Method
leaultlnf.
Ccwpatatlou
4
favduat
IP
Moletura
Corresponding
Weight par
100 pound* of
Dry Feed
Percent:
Savduat
B20
CHKO
Pound a of:
Sawduit
"/
a *°2
Hj Z
M2
Or I flea
Percant of
»2
°2
Measuramane Laboratory Resulting Computation Corresponding
Technique Determination Coapoaitloa t Analy*!* Ueljht per 100
Method Pounds of Dry
reed
Char
&
Moiatura
Oil
&
Kolature
Dry
Ctt
Oll-Cmt
Water
Oxrtao
"Loit
Carkon"
Welsh
&
Sanpla
Weigh
&
Sa«pla
Caapla
H20
Analyaia
t
CHNO
Analysis
H20
Analyala
&
CHSO
Analysis
Chroaiaco*
graph
Percent of:
C
H20
CHNO
Percent of!
Oil
H.O
CHNO
Percent o£:
-2 'CH4
*> C
rz c'
2 C4
Nitrogen
Balance
Hydro Ren
Balance
Oxynen
Balance
Carbon
Balance
Pounds of:
C
Pound* of:
Oil
H,0 I X
c;
Poundc dry
Pound* H.O
in 0(f-(j.
rounds C
-------
determination of the weight of carbon, water, hydrogen, nitrogen and
oxygen in the char for each run. Similar procedures allowed computation
of the amounts of water, carbon, hydrogen, nitrogen, and oxygen in the
condensed oil.
The dry non-condensible gas composition was obtained from gas chromato-
graphic determinations. Using the percent nitrogen found in the off-gas
and the total nitrogen input from the process air the amount of dry
pyrolysis gas was calculated. Investigations indicated that the nitrogen
in the feed, the char and the oil is small and can be ignored when
performing elemental mass balances.
The water content of the off-gas was obtained from a hydrogen balance. In
this calculation the difference between the sum of the input hydrogen from
the sawdust and associated moisture and the sum of the hydrogen in the
output char, oil and dry gas, (including the char and oil moisture) was
determined. Then this hydrogen was assumed to be associated with a
corresponding quantity of water and this value taken as the water content
of the off-gases. As a check on this procedure an oxygen balance was
made using that oxygen associated with the measured input feed and process
air, the measured char, oil and gas outputs and that calculated for the
water. The difference between the input oxygen and the output oxygen
was found to be never more than a few percent with an average for all
14 runs of only 0.8 percent. This then confirmed the assumptions inherent
in the hydrogen balance and gave confidence to the overall mass balance
procedures.
Upon summing up the weights of the carbon, oil, water, and dry gas in a
mass balance it was typically found that seven to 10 percent of the
output products were unaccounted for. Because of the confidence held in
the char measurements and the computed values of water and dry gas it
was felt that this lost material most likely was oil. While this loss
did not appreciably affect the mass balance it had a major impact on the
energy balance. This led to an additional computation, a carbon balance
to determine the "lost carbon."+ From the carbon balance it was found
that the amount of carbon missing from the products was on the average
very near that missing from the calculated mass balance; thus the surmise
that the "lost carbon" and the lost oil were the same was substantially
strengthened. This then was taken as fact in further analyses and the
mass and heat balances calculated with the computed values of "lost carbon."
Presented in Appendix B is a sample calculation for the results of run 7
illustrating the preceding discussion.
•fSince the carbon content of the dry pyrolysis oil is so large, it can be
considered for practical purposes as "liquid carbon." It was known from
the testing that considerable quantities of the oil were unaccounted for
and that the yields were well below those expected from the laboratory
results; therefore the suspicion that the lost carbon and the lost oil
were essentially the same was based on substantial but indirect evidence.
41
-------
Discussion of Results
The results of the experimental work are shown in Tables 4 and 5. A
summary of the most important data upon which the conclusions from this
investigation are derived is presented in Table 6. Study of the results
from run 4 and 5, 9 and 10, 7 and 16, shows conclusively that the effects
of agitation on product yields are unimportant.**
Comparison of the data from runs 10 and 18 indicate that tube geometry
probably has little effect on product yields, although a comprehensive
study of this parameter was not made.
From a study of the data from all the tests it appears that the effect
of bed depth on char yields is unimportant; however the deeper beds may
result in greater oil yields and therefore may be more desirable in
maximizing the production of the char-oil mixture.
The most dramatic effect and the one which overrides the importance of
any of the other test parameters is the air/feed ratio. This is illustrated
in Figure 19 which shows a plot of char yields as a function of air/feed
and Figure 20 which presents a graph of the percent of the available
energy in the char-oil mixture as a function of air/feed. These figures
are plots of all the test data at various bed depths,tube geometries,
feed rates, and with or without agitation. Clearly the air/feed ratio
is the dominant parameter and small values are the most desirable.
It is interesting to note in Figure 20 the value of the available energy
fraction extrapolated to zero air/feed. This value is nearly identical
with that obtained from the tube furnace tests at a minimum pyrolysis
temperature and shown in Figure 9. Since the pilot plant operating
conditions and those of the tube furnace become more nearly comparable
at zero air/feed this result strengthens the test findings and provides
a possible means of correlating the laboratory and the pilot plant test
data.
Presented in Figure 21 is an energy breakdown of the pyrolytic products,
including losses, as a function of air/feed. The data are plotted using
the results shown in Table 5 and no consideration is given to the various
values of bed depth, tube geometry, etc. The graph reinforces the earlier
results which indicate the primary influence of the air/feed ratio on
product yields. The figure graphically illustrates how the various energy
forms change with increasing air/feed and also demonstrates the generally
good closure of the energy balance.
**It is important to note that mechanical agitation has been shown in
previous studies with bulky wastes to have a pronounced effect on the
outcome of the testing. Thus the fact that in these tests with this
feed and this agitator the effects were unimportant should not be
generalized to less free-flowing solids.
42
-------
TABLE 4
OVERALL MASS BALANCE*
OUTPUT
Run
Number
4
5
9
10
17
18
19
6
7
8
12
13
15
16
Average
it
*A11 res
Char
Yield
(lb)
18.7
20.7
11.6
10. A
28.1
10.2
27.8
25.8
16.1
22.5
26.3
28.9
32.7
17.4
ilts are
Oil
Yield
(lb)
6.3
6.7
14.4
11.3
8.1
11.3
14.3
7.8
10.1
12.0
5.9
15.0
12.1
13.8
present
Off-Gaa
Yield
(lb)
70.4
84.2
110
92.0
60.2
89.0
61.6
57.2
102
53.6
82.9
61.5
40.5
78.9
id on a
Char
& Oil
(lb)
25.0
27.4
26.0
21.7
36.2
21.5
42.1
33.6
26.2
34.5
32.2
43.9
44.5
31.2
Dasis of
Water
(lb)
45.4
42.4
27.1
40.3
30.0
39.9
32.7
39.4
28.8
41.5
39.9
32.9
32.4
33.0
100 lb
Total
Output
(lb)
141
154
160
152
126
151
136
130
157
130
155
138
117
143
142
dry sawc
INPUT
Feed
(lb)
^100
100
100
100
100
100
100
100
100
100
100
100
100
100
ust.
Air
(lb)
47.4
53.1
70.4
63.8
38.2
58.0
41.6
27.2
55.8
34.9
45.3
37.8
22.0
49.2
Water
(lb)
7.8
8.3
6.4
6.4
3.9
6.1
7.9
5.8
5.8
6.8
6.6
7.3
3.6
4.7
Total
Input
(lb)
155
161
177
170
142
164
150
133
162
141
152
145
126
154
*" 152
Dif-
ference
(lb)
14
7
17
18
16
13
14
3
5
16
-3
7
9
11
10
OXYGEN BALANCE
Input
(lb)
58.7
59.6
63.8
60.5
54.5
58.8
56.9
54.2
60.5
55.5
57.3
55.8
50.4
52.5
56.8
Output
(lb)
61.8
63.0
59.0
59.1
52.1
58.8
46.3
58.8
59.4
53.1
65.0
Dif-
ference
(lb)
-3.1
-3.4
-4.8
-1.4
2.4
0
10.6
-4.6
7-1
2.4
-7.7
51.2 4.6
48.4 2.0
55.6
-3.1
56.3
.4
CARBON BALANCE
Input
(lb)
45.7
45.6
45.6
47.1
48.2
47.5
45.8
45.3
48.2
46.3
46.5
46.3
48.4
46.5
46.5
Output
(lb)
28.7
35.0
38.4
33.5
35.3
35.2
45.0
37.9
46.1
37.9
40.8
44.6
42.5
38.7
38.4
Dif-
ferencE
(lb)
17.0
10.6
7.2
13.6
12.9
12.3
.8
7.4
2.1
8.4
4.3
1.7
5.9
7.8
8.1
-------
TABLE 5
OVERALL ENERGY BALANCE *
OUTPUT*
Run
Number
4
5
9
10
17
18
19
6
7
8
12
13
15
16
Average
*A11 res
lln thou
C
Char
221
214
147
131
284
133
304
338
216
2.95
334
336
363
235
ults are
sands of
1 "
lemical
Oil
72.7
106
226
181
132
172
229
106
I 172
198
97.4
252
197
203
presen
Btu's.
Energy
Off-Gas
159
191
259
197
118
221
146
166
288
117
167
126
122
200
ed on a
"Lost"
Carbon
247
154
104
197
187
178
11.6
107
30.5
122
62.4
24.7
85.6
113
basis o
Le
Water
Vapor
51.8
50.2
31.3
46.4
34.3
47.1
38.7
45.0
32.9
47.4
46.8
37.0
37.1
38.4
: 100 Ib
tent & !
Off-Gas
3.2
4.2
5.7
4.4
2.4
5.6
4.3
2.6
4.7
2.5
5.6
2.0-
1.8
4.6
dry saw
Sensible
Char
5.3
3.0
3.3
2.1
7.3
2.7
8.3
7.4
5.0
6.6
7.0
7.4
8.5
6.5
lust.
Energy
Oil
1.3
1.3
2.9
2.3
1.6
2.3
2.9
1.6
2.1
2.4
1.2
3.0
2.4
2.8
Con-
Coolingi vective
Water Losses
18.7
17.3
22.0
26.6
20.3
14.0
16.6
5.6
20.0
15.7
13.0
15.3
5.5
12.8
6.7
6.5
6.5
6.6
6.7
6.6
6.7
6.5
6.5
6.6
6.6
6.5
6.6
6.7
Total
Output
787
747
807
794
794
782
768
786
778
797
742
810
828
823
789
INPUT1 Product Heatine
Feed
831
814
811
820
832
827
832
814
814
823
820
818
825
842
823
DIF-
FERENCE
44
67
4
26
38
45
64
28
36
26
78
RATIO
HEAT Otq
HEAT IN
.947
.918
.995
.968
.936
.946
.923
.966
.955
.968
.905
8 i .990
-3 , 1.004
19
.977
34
.959
Value
Oil
Char plus
(BTU/lb)
12.873
12r473
14,367
14.419
12.231
14,289
1?,fiQ4
13,439
14,788
14,335
13.528
12.711
12,733
14,128
-------
TABLE -6
SUMMARY OF TEST RESULTS
Run
Number
4
5
9
10
17
18
19
6
7
8
12
13
15
16
Bed
Depth
(In.)
18
18
27
27
27
27
27
39
39
39
39
39
39
39
Agi-
tation
no
yes
no
yes
no
no
no
no
yes
no
no
no
no
no
Number
Air
Tubes
4
4
3
3
3
2
2
2
2
2
2
2
2
2
Air/
Feed
(Ib/lb)
.474
.531
.704
.638
.382
.580
.416
.272
.558
.349
.453
.378
.220
.492
Feed
Rate
(Ib/hr)
291
246
184
184
195
189
186
491
202
226
237
118
346
222
Char*
Yield
(lb)
18.7
20.7
11.6
10.4
28.1
10.2
27.8
25.8
16.1
22.5
26.3
28.9
32.4
17.4
Oil*
Yield
(lb)
6.3
6.7
14.4
11.3
8.1
11.3
14.3
7.8
10.7
12.0
5.9
15.0
12.1
13.8
Lost*
Carbon
(lb)
17
10.6
7.2
13.6
12.9
12.3
.8
7.4
2.1
8.4
4.3
1.7
5.9
8.0
Mass:
Output/
Input
1.02
1.02
.94
.977
.98
.99-
.91
1.03
.95
.98
1.05
.96
.975
.98
Energy:
Output/
Input
.947
.918
.995
.968
.936
.946
.923
.966
.939
.968
.905
.990
1.004
.977
Available**
Energy Comments
(Percent)
65.1
58.2
58.8
62.1
72.5
58.4
65.6
67.7
50.6
74.7
60.1
74.9
78.3
65.4
The oxygen balance
was not good.
Due to the high pro-
cess rate there was
a significant loss
of oil from the con-
denser.
The oxygen balance
was not good.
At this low through-
put, there was a
significant amount of
oil condensing in the
unit with resulting
eratic flow.
*A11 results are presented on a basis of 100 lb dry sawdust.
**Energy available in char/oil divided by total available from sawdust feed.
-------
.40.
.35 -
.30
.25 .
.20
•o
0)
2
.10
.05
0
SYMBOL NOMENCLATURE
Bed
Depth
(inches)
18
Agitation
Yes No
A6D
*Test Number and Air Tube
Configuration (see Table 3)
,10
.20
.30 .40
Air/Feed (Ib/lb)
.50
.60
70
Figure 19
Fractional Char Yields Versus Air/Feed Ratio
-------
Closely corresponds to tube
furnace tests (see Figure 9)
90
80
70
2.
60
50
u
oo
40
30
20
10
SYMBOL NOMENCLATURE
Bed
Depth Agitat^n
(inches) Yes No
18 •
27 |
39 A
D
A
8DA A13D
D
17B
10B
*Test Number and Air Tube
Configuration (see Table 3)
.2 .3 .4
Air/Feed (Ib/lb)
.5
.6
.7
Figure 20
Percent Available
Energy in Char-Oil Mixture
47
-------
oo
10Q
90
80
-------
Figure 22 shows a plot of the non-condensible gas heating value as a
function of air/feed. The scatter in the data is greater than experienced
elsewhere but there is a definite trend toward a reduced heating value
as the air/feed increases. Check of the nitrogen content of the gas
shows a corresponding increased percentage which helps explain the lower
heating values. Thus while the total heat available from the gas per
pound of dry feed increases with increasing air/feed, the heat content
of the gas is diminished.
Figure 23 presents a combination of data from Table 5 together with
computed heat energy requirements for processing and drying the feed. The
computed curve is based on an assumed 1500 Btu required to evaporate each
pound of water in the feed and 360 Btu/lb dry feed of raw heat energy
required to process the dry feed. This latter figure arises from an
assumed 50% derating of the engine power plant for the portable unit, a
requirement for 170 hp (see Table 7) and an assumed thermal efficiency
of 15 percent. Since the energy required to dry and process the feed
must be supplied by the non-condensed gas, the figure provides a means of
determining the required air/feed ratio and the available energy in the
char-oil mixture for a given feed percent moisture*. To illustrate, at a
50 percent moisture composition, 1860 Btu/lb dry feed would be required
for drying and processing. At an air/feed ratio of approximately .47,
the available energy in the non-condensible gas would meet these energy
requirements and at this same air/feed value the heat available in the
char-oil mixture would be approximatley 5500 Btu/lb dry feed with an
overall conversion efficiency of about 65 percent.
Clearly as the feed moisture percent becomes much greater than 50 percent
the energy available in the char-oil mixture drops off sharply.
*Moisture composition is defined as pounds of water per pound of mixed feed.
49
-------
250
200
Ul
o
150
(1)
J-l
OJ
50 r
LEGEND
O Bed Depth=18 inches
D Bed Depth=27 inches
A Bed Depth=39 inches
.1
.3 .4 .5
Air/Feed (]b/lb)
Figure 22
Heating Value of Non-Condensible Gas
.6
.7
.8
-------
JO' .8 .6
Air/Feed (drfc) Ib/lb
.2
XI J
4J
m
20 40 60 80 IOC
Feed Percent Moisture
1,000
2,000
Assumptions:
, 1) Gross heat energy
),000 required to process
one pound dry feed=
360 Btu
,000
2) 1500 Btu required
in drier to evaporate
5,000 one pound of water
5,000
Figure 23
Effects of Feed Moisture on Available
Energy from Char-Oil Mixture
51
-------
SECTION VI
MOBILE PYROLYSIS SYSTEM PRELIMINARY DESIGN
Presented in this section is a preliminary design of a 200 ton/day
(assuming 50 percent moisture) mobile pyrolysis system. In addition
to the design, the results of a simplified economic analysis are also
shown. But before discussing this work, the overall concept of the
portable system should be described. Figure 24 presents a schematic view
of the proposed manner of operation of the system. As pictured, several
mobile units would operate in zones with a large thermal conversion plant
at their center. The several units would convert various agricultural
and forestry wastes into the char-oil fuel which would be transported
to the thermal conversion plant. By proper scheduling and by using the
constantly produced wood wastes as a means of leveling out the seasonal
fluctuations in the agricultural waste production, a fairly constant
supply of wastes could be provided.
As conceived, one char truck could service three or four pyrolysis units
and likewise only one tractor for perhaps seven or eight complete systems
would be required to move them from site to site. The char trucks would
have a closed trailer which would also serve as a char-oil storage container
and be exchanged twice daily.
The portable system was designed with certain basic ground rules which
are listed below:
It must be completely self-sustaining
It must produce no land, water or air pollution
It must be transported readily and with no special highway
permits, i.e., its length should not be greater than 55 feet,
its width is eight feet, its height is not more than 13 feet
six inches and its weight is less than 73,000 pounds.
In addition to these basic limitations, it was assumed that:
System does not require any outside source of water for cooling
The system would comprise two trailers
52
-------
Figure 24
Mobile Pyrolysis System Concept
53
-------
The start-up would be accomplished using propane
The oil condenser would operate at a temperature greater than
the off-gas dew point to avoid moisture condensation
A 50 percent derated gasoline engine operating on the low Btu
pyrolysis gas would provide the power required to operate the
system
The design rated capacity of the system would be based upon the
experience gained with the Cordele, Georgia, demonstration
unit.
The feed, and the resulting char, because of its typically low
thermal conductivity, would serve as an insulator on the sides
of the unit. This would prevent not only the necessity for
and associated weight of a ceramic insulator but also avoid the
problems of transporting such a brittle, fragile system
SYSTEM DESCRIPTION AND DRAWINGS
The overall portable pyrolysis system is shown schematically in Figure 25.
Examination of the figure indicates that after leaving the hammer mill,
the pulverized wet bark, together with the sawdust enters the drier and
from there the mixture is conveyed to the waste converter unit. The char
produced is emptied into a mixer where it is combined with the pyrolysis
oil. The gases produced in the converter pass through the cyclone and
into the condenser where the higher boiling point oils are removed and
mixed with the char. The noncondensed gas then is used to operate the
engine generator system and also to supply heat to the drier.
Presented in Figure 26 and 27 are preliminary design drawings of the two
trailers which make-up the system. The dominant feature in Figure 26 is
the drier. The location and geometry of this unit largely governs the
design of the elements on this trailer and significantly influences the
overall system layout. Likewise in Figure 27 the major component is the
waste converter, but interestingly the location of this unit has less
effect on the overall design than the drier. The drawings show the
trailers in their stowed configurations to illustrate that adequate space
is available for all the required components. Deployment of the system
would mainly involve moving the conveyors from their stowed to their
operational locations, connecting up the flexible pipe between the off-gas
system and the drier, and unloading the feed hopper by use of a collapsible
ramp stowed underneath.
In the operational mode, the trailers would be located adjacent to one
another as shown in Figure 28, which presents a plan view of the deployed
system. Expanded metal platforms, not shown in Figures 26 and 27 would be
folded out from the trailer sides to provide a work space for the operating
crew.
54
-------
Ln
Cold Water
Finished Product—
Charcoal and Oil Mixed
Figure 25
Mobile Pyrolysis Unit Preliminary
Process Flow Diagram
-------
Figure 26
Plan and Elevation Views of Trailer I
CAS
FROM CONDENSER
Ul
WET SAWDUST
AM) BARK
ttffi
GAS TO MU.H-CYCUHC
f---'.._. ^ r--x
! f?;iY^ fe\^
• I \ .' I I. • '. I < I
~ ^ « •< - ~ "> 'N
/ » / «. / \ V^13-'!1 / '.V"-""-'^ /" •' \ ' \
^ ^_Y__^__»__j. ,^_ _ x •'^'^'S^ Z- -H-T" rf V - * _ _ /. 1 u i _j
" ' ' ^ ~"J
' , Yv ' » '!!! \ v ','**' * > \ ' \ /
I _ _=K- J-V_ -»_^vl.J :J»*J.|_ i_' j^ _ _««_ w_ __ _^ .
\ : . F ',' - \\
' S S S / S /
///S/S/S////S
-------
Figure- 27
Plan and Elevation Views of Trailer II
(36' \£)
'
Ui
(G.SES
DRYER
-PROCESS AIR
TO CONVERTOR
-------
00
LEGEND:
Front end loader
Bin conveyor
Receiving bin
Conveyor mill
Hammer mill
Drier
Feed conveyor
Converter
Cyclone
Condenser
Condenser cooling fan
Draft fan
Combustion air fan
Off-gas burner
Drier fans
Burner exhaust
Drier exahust duct
Cyclone
Process air blotter
Generator
Engine
Cooling water radiator
Compressor
Conveyor
Char oil mixer
Char storage bin
Control room
Agitator
Front end loader storage
Cat walk
Engine blower
Figure 28
Plan View of Deployed Mobile Pyrolysis System
-------
Figure 29 presents two elevation crossectional views of the pyrolysis
unit to be used. Also shown are typical types of agitators that might
be employed to increase throughput. In addition, a novel insulating
technique, involving the char and feed itself as a means of minimizing
heat loss, is shown. The "char shelves" would simply trap a portion of
the downward moving waste and then this material because of its relatively
low conductivity would resist the passage of heat through the walls. A
fibrous, non-ceramic insulator would act as a back-up system. By use
of this method of providing an expendable insulator, most of the problems
of transporting the unit would be circumvented. In fact this is a key
concept in making the entire system transportable.
Finally, Table 7 presents a complete list of components and their
characteristics used in the mobile system preliminary design. To
illustrate the table, component number 19 (reference Figure 28) is the
process air blower, Dresser Model 3514-J, producing 542 cfm at one psig,
requiring 3.6 hp and weighing 640 pounds. There are doubtless many other
commercially available components which could serve as well as those listed
in the table, and therefore the list is for illustrative purposes primarily.
However, the table shows that components either commercially available
now and/or readily fabricated could be assembled to provide a system with
the desired characteristics. Moreover the system size, weight and load
distribution would be within the legal limits.
PRELIMINARY ECONOMIC ANALYSIS
The preliminary economic analysis of the portable waste converter was limited
to a study of only one system within an array of systems servicing wood yards
and was made on the basis of the current technological development of the
system. Assumptions were made, however, regarding the costs of sharing of
equipment among systems and the supervision costs of a group of systems. It has
been also assumed that by proper scheduling the systems can be kept continuously
operating except for down time between waste sites.
Listed below are more detailed assumptions used for the economic analysis
of an individual system:
Interest rates are 9.5 percent
. System costs were computed by scaling-up the actual Cordele
facility costs using a 1/2 power law and then multiplying the
results by 2.5 to allow for manufacturer profit, inflation and
increased complexity of the mobile system. (For a 100 ton/day
dry system the costs are about $405,000.)
. A total capital depreciation of ten years is taken
The mobile unit is assumed to service each waste producer in
its circuit once a year
59
-------
Figure 29
Elevation-Crossection
Views of Mobile Pyrolytic Converter
-------
TABLE 7
LIST OF EQUIPMENT
FOR PORTABLE PYROLYSIS SYSTEM
Part
Number Part Name Function of the Part
1.
2.
3.
4.
5.
6.
7.
8.
9.
Front end loader To load wet feed from ground to
bin conveyor.
Bin conveyor. To transfer wet feed from front
loader to receiving bin.
Receiving bin Receives wet feet to feed hammer
mill.
Hanmer mill Transfers wet feed from receiving
conveyor bin to hammer mill.
Hammer mill Pulverizes feed.
Drier Drys the wet feed.
Feed conveyor Transfers dry feed from drier to
converter.
Converter Produces char and oil from the
dry feed.
Cyclone Separates the particles from the
converter output gases before
Description
Tractor-shovel with
hydrostatic-drive
Belt conveyor:
10' long, 12" wide
Fabricated container
including screw con-
veyor: 10' long,
12" diameter
Belt conveyor:
20' long, 12" wide
Hammer mill
Ducting system con-
tainer, 36" diam-
eter screw con-
veyor
Belt conveyor 30'
long, 12" wide.
10' long, 12" wide
See pp. 60 in
report
Dust collector
cyclone
Made By Model No,
International H-25B
and Hough
Stone
Fabricated
(Link-Belt)
Stone
Williams C-32
Link belt &
duct work
fabricated
Stone
Fabricated
Fabricated -
Capacity H.P.
1 yard of N/A
wet feed/
load
8 ton/hour 1/2
of wet feed
320 cubic 1/3
feet, 8 ton/
hour
8 ton/hour 3/4
of wet feed
3-5 ton/hour 75
of 2" bark
8 ton/hour 1
of wet feed
4 ton/hour 1-j-
of dry feed
4 ton/hour 3
of dry feed
_ N/A.
Carried On
Weight Trailer No.
6,200
850
850
1,700
6,000
4,700
3,400
22,100
1,128
i
ii
ii
i
i
i
i
ii
ii
entering the condenser.
-------
TABLE 7 (CONTINUED)
CT-
Part
Number Part Name
10. Condenser
11. Condenser cooling
fan
12. Draft fan
13. Combustion air
fan
14. Off-gas burner
15. Drier fans
Function of the Part
Condenses the oil in the off-
gas from the converter.
Provides cooling for the oil
condenser
Transfers off-gas from reactor to
the off-gas burner.
Supplies air to the off-gas burner
burner.
Bums non-condensible off-gas to
provide heat for drier.
Transfers hot. combustion gas from
off-gas burners through drier
and drier cyclone.
Description Made By
Single-Pass cross- Fabricated
flow
Industrial American
exhauster Air Filter
Industrial American
exhauster Air Filter
Industrial American
exhauster Air Filter
Horizontal Fabricated
cylindrical burner
2 Industrial American
exhausters Air Filter
Model No.
_
AAF Type
K, Adjusti-
ble Drive
2 hp motor
size 11
AAF Type
K, Size 11
Adjustible
drive, 5
hp motor
AAF Type
K, Size 19
Adjusclble
drive, 15
hp motor
N/A
AAF Type
K, Size 17
x 2 units,
Adlustible
drive, 20
hp motor
Carried on
Capacity H.P. Weight Trailer No.
N/A 1 x 10 5,940'
Btu/hr
from
500-F to
120°F
1800 c.f.a. 1-i- 195
at 3" of
water
pressure
drop
2100 c.f.m. 5.02 195
at 10" of
water
pressure
drop
lO.OOOc.f.m. 12.9 670
at 5" of
water
pressure
drop
8 ton/hour N/A 5,080
Gas M-26
from 150'F
to 700°F
8000 c.f.m. 37.4 for 1,300
at 10" of two
water units
pressure
drop
II
II
I
I
I
I
16. Burner exhaust
Exhausts excess combustion gas
not required for drying.
Burner
stack
PART OF THE BURNER
-------
TABLE 7 (CONTINUED)
Part
Number Part Name Function of the Part
17.
18.
19.
20.
21.
22.
23.
24.
Drier exhaust duct Duct from drier to drier cyclone.
Drier cyclone Separates particles from drier
exhaust before venting to
atmosphere.
Process air blower Supplies process air to the
convertor.
Generator Supplies electrical power for
the unit.
Engine Drives the generator.
Cooling water Provides cooling water for
radiator process air tubes.
Compressor Supplies air to pneumatic
components.
Output Conveyor Transfers char and oil from
mixer to storage bin.
Description
Steel duct inlet
dimension 12" x
30"
Multi-clone
Roots Whispair Max,
rotary positive
blower
A-C generator
60 cycles
Derated gasoline
engine
Flat radiator
Automotive air
compressor
Belt conveyor,
12" wide,
10" long
Made By
Fabricated
Western-
Precipita-
tion
Dresser
Maraton
Haukesha
General
Radiators
Champion
Stone
Model No.
N/A
12 VMU
Size 8-2
3514-J,
Flange
mounted
drip-
proof
L1616G
_
VR 3-8
_
(Ib) Carried On
Capacity H.P. Weight Trailer No.
16,000 N/A 2,500
c. f .m.
16,000 N/A 2,300
c.f .m.
542 c.f.ra. 3.6 640
at 1 psig
pressure
drop
120 KW 160 "\
\ 9 000
Derated 338 at (
50 percent 1800
rpm )
35 G.P.M. 10 1,300
12.8 c.f.m. 3 500
at 140-170
psi
2 ton/hour 1/3 850
of char &
oil
I
I
II
II
II
II
II
II
-------
TABLE 7 (CONTINUED)
Part
Number
25.
26.
27.
28.
30.
31.
32.
33.
Part Name
Char and oil mixer
Char and oil
storage trailer
Control room
Agitator
Cat Walk
Engine blower
Trailer I
Trailer II
Function of the Part
Mixes the char from the converter
and the oil from the condenser.
Stores the oil and char.
Contains operating controls for
the unit.
Prevents bridging in the reactor
and promotes uniform flow of
material.
Walking ramp to provide access
to system components.
Transfers and compresses off-
gas fuel to engine.
Carries components: 1, 4, 5, 6,
7, 12, 13, 14, 15, 16, 17, 18,
and 30.
Carries components: 2, 3, 8,
9, 10, 11, 19, 20, 21, 22, 23,
Description
Container, screw
conveyor 9" diam-
eter 5" long
Enclosed trailer
5" x 6" room
P A R V OF T H
Expanded metal
Roots whispair
Max rotary
positive blower
25-ton tandem axle
level deck load
runner, 445" long
25-ton tandem axle
level deck load
Made By
Fabricated
(Link-Belt)
Fruehauf
Fabricated
E C 0 N V E
Fabricated
Dresser
Fruehauf
Fruehauf
Model No.
_
JG9-F2-45
Top close
N/A
R TO R
N/A
1704-J
Direct
coupling
drive
C25L-J2
445" long
C25L-J2
445" long
Capacity H.P.
4000 Ib/hr 1/4
of material
with density
of 40 Ib/ft
58,280 Ib. N/A
N/A N/A
N/A N/A
115 c.f.m. 1.7
at 2 psig
and 7000
rpm
50,000 Ib N/A
50,000 Ib N/A
(Ib) Carried On
Weight Trailer No.
615 II
15,000
1,500 II
200 Ib I
for each II
trailer
142 II
44,435
55,000
24, 25, 27, 29, 30, and 31.
runner, 445" long
-------
The time on site would average two to three weeks, assuming
medium size sawmills
The distance between sawmills is small enough so that the
travel time is a minor part of the total down time between
sites
The total down time between sites is two days
Wood wastes are typically 50 percent water
If a disposal charge is made, it is $3/ton of raw wastes
The crew operating the unit comprises a cadre, permanently
assigned, and local filler personnel
The crew has a crew boss who makes $15,000/year and one or
more lead men at $12,000/year. The filler personnel make
$7,500/year
It takes two men to operate the unit and there are two or
three shifts
. Maintenance is conducted on the weekends
The system operates 250 days/year
Supervision overhead is $12,000/year
Shared equipment expenses are $6,000/year or $9,000/year
depending on the number of shifts
The drier requires 1500 Btu of chemical energy from the
non-condensible gas to evaporate each pound of water in the
as received feed
The derated engine operates at 15 percent thermal efficiency.
Thus 360 Btu chemical heat energy are required to process
one pound of dry feed
One pound of dry feed produces .456 pounds of char oil mixture
including a typical 10 percent moisture fraction
The heating value of the char-oil mixture is 11,500 Btu/lb.
This allows for the 10 percent water fraction
The dominant influence on the results of the analysis is the fuel price
which can be obtained for the char-oil mixture. Because so many coal
prices are possible, depending upon whether "contract" or "spot market"
values are used it was not practical to select just one char-oil fuel
price. Therefore three values, i.e., $20/ton, $35/ton, and $50/ton were
65
-------
employed in the analysis. It may be, because of the physical character
of the char-oil mixture and because the quantities produced initially
will likely not be large, that it is better suited for the spot market
which relies heavily on small to medium capacity stoker fixed systems.
Communications with stoker manufacturers indicate that the char-oil
mixture will burn readily on most stoker systems; in some cases, however,
minor modifications to the grate would be required. Likewise there is
also the possibility that the mix could be used with packaged boilers,
modified with special burners. The low sulfur character of the fuel
would be especially important to the small to medium size boiler operator,
since flue gas clean-up equipment is proportionately a much higher capital
cost item than for large utility boilers. Regardless of the market,
the low sulfur character of the fuel should make it more valuable than
a high sulfur coal with a comparable heating value.
[ [
Thus with all these assumptions the economic analysis was made and the
results are presented in Figures 30, 31 and 32, which, for a given
fuel cost, show the net income, before taxes, of units as a function of
their operating capacity. Parameters investigated are the number of
operating shifts and whether or not a disposal credit is charged. These
figures together illustrate the dominant influence of the price of the
fuel on income and strongly suggest that three shift operation is highly
desirable. Likewise it can be seen that the effects of collecting a
$3/ton of raw wastes disposal credit can have a significant impact on
the net profit. Finally these figures demonstrate the great advantage
to be gained in uprating the system capacity.
Figure 33 represents a cross-plot of the data from Figures 30, 31, and 32
for a 100 (dry) ton/day unit, with net income plotted as a function of
fuel prices. The figure reinforces the importance of three shift
operation to the system economics and again illustrates the influence
on profit of a disposal credit. From the figure it appears that even
for 16 hr/day operation and without a disposal credit, the break-even
point would be $20/ton. And clearly as the fuel price increases, the
net income goes up very rapidly.
From this work, it appears that on strictly economic grounds, a strong
case can be made for the profitability of the portable waste conversion
unit. And when the more intrinsic advantages to society, the environment
and our national economics are included, the argument for the development
of such a system is compelling.
-H-Presented in Appendix C is a sample calculation from this analysis.
66
-------
500
400
£ 300
£
OB
I
§
o
2
200
1OO
Including disposal charge and working 24 hours a day
Including disposal charge and
working 16 hours a day
Not including disposal charge
and working 24 hours a day
Not including disposal charge
and working 16 hours a day
0 25 50 75 100 125 150
Dry Waste Feed Capacity (ton/day)
175
200
Principal Assumptions:
1. Fuel is worth $20/ton
2. Interest—9.5 percent
3. Depreciation—10 years
4. Raw wastes are 50 percent moisture
5. Disposal charge is $3.00/ton of wet sawdust
6. The results apply to a medium size sawmill
Figure 30
Preliminary Analysis
Net Income of a Mobile Waste Converter with Varying
Capacity--Fuel Price $20/ton($.87/106BTU)
67
-------
800
700
600
X-N
rt
^500
CO
2400
e 300
o
o
c
H
200
100
0
Including disposal charge and
working 24 hours a day
Not including disposal charge-
and working 24 hours a day
Including
disposal
charge and working
16 hours a day
•Not including disposal charge
and working 16 hours a day
25 50
75
100
125
150 175
200
Dry Waste Feed Capacity (ton/day)
Principal Assumptions:
1. Fuel is worth $35/ton
2. Interest--9.5 percent
3. Depreciation--10 years
4. Raw wastes are 50 percent moisture
5. Disposal charge is $3.00/ton of wet sawdust
6. The results apply to a medium size sawmill
Figure 31
Preliminary Analysis
Net Income of a Mobile Waste Converter
With Varying Capacity—Fuel Price $35/ton ($1.52/106BTU)
68
-------
900-
800
700
600
"8 500
«J
CO
3
~400
§
o
o
w 300
200
100
Including disposal
charge and working
24 hours a day
Not including disposal
charge and working 24
hours a day
J_
^Including disposal
charge and working
16 hours a day
-Not including disposal charge
and working 16 hours a day
25 50 75 100 125 150 175 200
Dry Waste Feed Capacity (ton/day)
Principal Assumptions:
1. Fuel is worth $50/ton
2. Interest--9.5 percent
3. Depreciation--10 years
4. Raw wastes are 50 percent moisture
5. Disposal charge is $3.00/ton of wet sawdust
6. The results apply to a medium size sawmill
Figure 32
Preliminary Analysis
Net Income of a Mobile Waste Converter
With Varying Capacity—Fuel Price $50/ton($2.17/106BTU)
69
-------
800
700
M
8 600
CO-
4) 500
e
w
CO
o
JC
•U
400
8 300
c
200
100
Including disposal charge and
working 24 hours a day
Not including disposal charge-
and working 24 hours a day
Including disposal charge-
and working 16 hours
per day
Not including dis-
posal charge work-
ing 16 hours per
day
5 10 15 20 25 30 35 40 45 50 55 60 65 70
Price of Fuel ($/ton)
3 .50 1.0 1.5 2.0 2.5 3.0
Price of Fuel ($/10 Million Btu)
Converter with Varying Prices
Principal Assumptions:
1. Interest--9.5 percent
2. Depreciation--10 years
3. Raw wastes are 50 percent moisture
4. Disposal charge is $3.00/ton of wet sawdust
Figure 33
Preliminary Analysis
Net Income of a 100 ton/day (Dry) Waste
70
-------
SECTION VII
REFERENCES
1. Kemp, Clinton C., Testimony before the Subcommittee on Energy of
the Committee on Science and Astronautics, U. S. House of
Representatives, Ninety-Third Congress, June 13, 1974.
2. Inman, Robert E. and Allich, John A., Testimony before the
Subcommittee on Energy of the Committee on Science and
Astronautics, U. S. House of Representatives, Ninety-Third
Congress, June 13, 1974.
71
-------
SECTION VIII
APPENDICES
Page
A. Laboratory Test Results 70
B. Sample Calculation of Chemical,
Mass and Energy Balances used
to Reduce Test Data 92
C. Economic Analysis - Sample Calculation for a 100 Ton/Day
Unit Working 24 Hours a Day
Including Disposal Charge 101
D. Unit Conversion Tables 105
72
-------
APPENDIX A
LABORATORY TEST RESULTS
This appendix contains the results of the laboratory tests described
in Section V. The data is presented and is discussed in the following
order:
Laboratory analyses for the 14 runs
Trace element analyses for runs 7 and 15
Stack emissions
Viscosity data for pyrolytic oils
Boiling point data for pyrolytic oil
Laboratory Analyses
Presented in Tables A1-A14 are the routine laboratory analyses of the
feed, char, oil, and off-gases used in the heat and mass balances. In
most cases at least two values of each parameter were obtained. Attention
is especially directed to the footnotes which clarify many of the numbers
tabulated.
Trace Element Analyses
Presented in Table A-15 are trace element analyses for runs 7 and 15.
In these tests, usually two values were obtained, however, only the
average of these is tabulated for the sake of brevity.
Stack Emissions
Stack emissions data for run 17 are presented below:
CO - 10 ppm
S02 - 1 ppm
73
-------
H S - 0 ppm
NOx - 1 ppm
The vortex burner was not operating properly during this test and some
variations in the CO level were observed.
Presented in Figure A-l is the viscosity of a typical pyrolytic oil as
a function of temperature. As expected the viscosity reduces dramatically
with increasing temperature.
Presented in Figure A-2 is a plot of the percent of the oil sample
remaining as it is heated from 10°C to 300°C. The smooth, continuous
shape of the curve and the lack of any discrete boiling points for the
mixture indicates the presence of numerous hydrocarbons.
74
-------
Ul
Table A-l
LABORATORY ANALYSIS
Run 4
Percent
Composition
Water
Ash
Acid Insol-
uble Ash
Volatiles
Carbon
Hydrogen
Nitrogen
Oxygen
t
Heating Value
Test
1
6.96
1.13
0.24
-
46.4
5.7
0.3
39.0
7674
Feed
Test
2
7.54
1.00
0.31
-
45.0
5.4
0.1
38.4
7749
Average
7.25
1.07
0.28
-
45.7
5.6
0.2
38.7
7712
Test
1
3.81
11.01
6.94
5.29
79.4
1.1
0.1
13.5
11,152
Char
Test
2
4.24
10.53
6.09
5.41
67.3
1.2
0.0
13.5
11,523
Oil
Test Test
Average 1 2 Average
4.03 30.7 - 30.7
10.77 -
6.52 - -
5.35 - -
73.3 47.2 46.5 46.9
1.2 5.9 6.0 6.0
0.1 0.4 0.3 0.4
13.5 53.8 41.9 47.9
11,337 - - 11,900*
Off
Non-
Condensible
Components
N2
CO
co2
H2
CH4
C2
s
J
C,
t
Heating
Value
**
Molecular
Weight
Gas
Percent
46.7
17.5
14.3
11.8
4.3
0.51
0.13
0.03
2,260*
26,6
**
Heating value is in Btu/pound
These values of heating value were calculated from the elemental composition. They were used in the heat balance.
Molecular weight is in pounds/mole
-------
Table A-2
LABORATORY ANALYSIS
Run 5
Percent
Composition
Water
Ash
Acid Insol-
uble Ash
Volatiles
Carbon
Hydrogen
Nitrogen
Oxygen
f
Heating Value
Test
1
7.81
1.23
0.48
-
45.7
5.8
0.4
38.7
7549
Feed
Test
2
7.52
1.14
0.56
-
45.4
5.8
0.4
39.0
7536
Average
7.67
1.19
0.52
-
45.6
5.8
0.4
38.9
7542
Test
1
4.07
4.38
1.72
-
71.5
3.8
0.0
26.6
10,166
Char
Test
2
4.22
4.12
1.53
-
71.9
3.6
0.0
26.5
9,661
Oil
Test Test
Average 1 2 Average
4.15 66.3 - 66.3
4.25 -
1.63 -
_ _ _, _
71.7 36.7 37.8 37.3
3.7 7.9 8.0 8.0
0.0 0.2 0.4 0.3
26.6 58.2 51.7 55.0
9,914 15,900 18,900 15,800*
Off
Non-
Condensible
Components
N2
CO
co2
H2
CH,
C2
C3
C,
f
Heating
Value
**
Molecular
Weight
Gas
Percent
46.3
21.3
15.5
10.8
4.4
0.54
0.14
0.039
2,270*
27.3
Heating value is in Btu/pound
These values of heating value were calculated from the elemental composition. They were used in the heat balance.
*
Molecular weight is in pounds/mole
-------
Table A-3
LABORATORY ANALYSIS
Run 6
Percent
Composition
Water
Ash '
Acid Insol-
uble Ash
Volatiles
Carbon
Hydrogen
Nitrogen
Oxygen
4.
Heating Value
Test
1
5.20
1.03
0.21
—
44.9
5.7
0.2
40.9
7683
Feed
Test
2
5.68
0.90
0.30
—
45.7
5.6
0.1
41.6
7728
Average
5.44
0.97
0.26
-
45.3
5.7
0.2
41.3
7705
Test
1
0.60
5.03
1.51
22.43
75.8
1.8
0.3
'19.5
13,138
Char
Test
2
0.45
4.92
1.77
19,44
83.4
1.9
1.1
13.1
13,062
Oil
Test Test
Average 1 2 Average
0.52 57.6 - 57.6
4.98 -
1.64 -
20.94 -
79.6 31.9 33.3 32.6
1.9 8.3 7.9 8.1
0.7 0.0 0.3 0.2
16.3 60.3 60.5 60.4
13,100 - - 13,600*
Off
Non-
Condensible
Components
N2
CO
CO
£,
H2
£.
CHA
A
C2
c3
J
C4
f
Heating
Value
**
Molecular
Weight
Gas
Percent
36.2
21.1
22.4
13.2
6.9
1.2
0.4
0.1
2,900*
27.6
Heating value is in Btu/pound
*
These values of heating value were calculated from the elemental composition. They were used in the heat balance.
**
Molecular weight is in pounds/mole
-------
CO
Table A-4
LABORATORY ANALYSIS
Run 7
Percent
Composition
Water
Ash
Acid Insol-
uble Ash
Volatiles
Carbon
Hydrogen
Nitrogen
Oxygen
+
Heating Value
Test
1
5.25
1.39
0.43
-
45.6
5.6
0.8
42.5
7726
Feed
Test
2
5.67
0.78
0.45
-
45.8
5.5
0.8
42.5
7675
Average
5.44
1.09
0.44
-
45.7
5.6
0.8
42.5
7700
Test
1
1.13
5.88
2.80
5.35
88.9
5.9
.0.3
4.9
13,287
Char
Test
2
1.09
5.90
2.46
5.92
84.8
5.5
0.9
8.8
13,208
Oil
Test Test
Average 1 2 Average
1.11 66.5 - 66.5
5.89 -
2.63
5.64 -
86.9 44.02 44.1 44.0
5.7 7.44 7.51 7.48
0.6 0.95 0.90 0.92
6.8 41.9 45.2 43.6
13,248 - - 16,300*
Off
Non-
Condensible
Components
N2
CO
co2
H2
CH4
C2
s
C4
f
Heating
Value
**
Molecular
Weight
Gas
Percent
38.6
25.6
14.8
13.2
4.82
0.81
0.13
0.02
2,820*
26.3
**
'Heating value is in Btu/pound
*
These values of heating value were calculated from the elemental composition. They were used in the heat balance.
Molecular weight is.in pounds/mole
-------
Table A-5
LABORATORY ANALYSIS
Run 8
Percent
Composition
Water
Ash
Acid Insol-
uble Ash
Volatiles
Carbon
Hydrogen
Nitrogen
Oxygen
4-
Heating Value
Test
1
6.51
2.26
1.24
_
46.7
5.7
0.1
41.0
7704
Feed
Test
2
6.19
2.11
1.13
-,
45.8
5.6
0.0
40.1
7708
Average
6.35
2.18
1.18
_
46.3
5.7
0.1
40.6
7706
Test
1
1.13
6.57
3.12
11.16
85.6
1.6
0.3
5.4
12,994
Char
Test
2
1.04
6.62
3.19
10.59
85.8
1.8
0.8
5.4
12,919
Oil
Test Test
Average 1 2 Average
1.08 57.2 - 57.2
6.59 - -
3.16 - -
10.87 -
85.7 52.7 45.8 49.3
1.7 7.6 8.0 7.8
0.5 0.4 0.7 0.6
5.4 40.1 45.8 43.0
12,956 - - 16,500*
Off
Non-
Condensible
Components
N2
CO
CO
2.
H0
2
CH.
4
C.
2
C0
3
C,
4
4-
Heating
Value
**
Molecular
Weight
Gas
Percent
48.6
14.9
18.7
9.8
4.48
1.69
0.11
—
2,180*
27.9
**
Heating value is in Btu/pound
*
These values of heating value were calculated from the elemental composition. They were used in the heat balance.
*
Molecular weight is in pounds/mole
-------
Table A-6
LABORATORY ANALYSIS
Run 9
Percent
Composition
Water
Ash
Acid Insol-
uble Ash
Volatiles
Carbon
Hydrogen
00
o
Nitrogen
Oxygen
j.
Heating Value
Test
1
6.21
1.02
0.82
-
45.3
5.9
0.8
46.5
7720
Feed
Test
2
5.88
1.05
0.86
-
45.8
5.0
0.2
46.8
7536
Average
6.05
1.04
0.84
-
45.6
5.5
0.5
46.7
7628
Test
1
1.81
9.52
5.04
7.36
80.6
1.4
0.5
9.0
12,536
Char
Test
2
1.69
9.44
5.00
7.51
80.8
1.4
o.i
7.2
12,542
Oil
Test Test
Average 1 2 Average
1.75 60.4 - 60.4
9.48 - -
5.02 -
7.44 -
80.7 44.1 43.1 43.6
1.4 7.6 7.6 7.6
0.3 0.5 0.2 0.4
8.1 47.0 48.2 47.6
12,539 - - 15,700*
Off
Non-
Condensible
Components
N2
CO
co2
HO
2
CH.
4
C.
2
C,
3
C,
4
4-
Heating
Value
**
Molecular
Weight
Gas
Percent
45.2
19.2
15.4
11.5
4.4
0.7
0.2
_
2,350*
26.8
**
Heating value is in Btu/pound
These values of heating value were calculated from the elemental composition. They were used in the heat balance.
Molecular weight is in pounds/mole
-------
00
Table A-7
LABORATORY ANALYSIS
Run 10
Percent
Composition
Water
Ash
Acid Insol-
uble Ash
Volatiles
Carbon
Hydrogen
Nitrogen
Oxygen
t
Heating Value
Test
1
5.97
1.26
0.50
-
47.3
6.0
0.3
43.3
7674
Feed
Test
2
6.09
1,29
0.51
-
46.8
5.9
0.2
44.6
7746
Average
6.03
1.28
0.51
-
47.1
6.0
0.3
44.0
7710
Test
1
2.25
9.31
4.50
10.60
83.9
1.7
0.6
6.0
12,290
Char
Test
2
2.33
9.13
4.47
11.20
85.6
1.7
0.7
5.4
12,293
Oil
Test Test
Average 1 2 Average
2.29 70.9 - 70.9
9.22
4.49 - -
10.90 -
84.8 47.7 51.3 49.5
1.7 8.0 7.0 7.5
0.7 0.5 1.3 0.9
5.7 46.7 36.6 41.7
12,292 - - 16,200*
Off
Non-
Condensible
Components
N2
CO
co2
HO
2
CH.
4
C2
C3
C4
t
Heating
Value
**
Molecular
Weight
Gas
Percent
47.4
19. j
12.3
9.7
3.8
0.47
0.09
-
2140*
27.0
**
Heating value is in Btu/pound
These values of heating value were calculated from the elemental composition. They were used in the heat balance.
*
Molecular weight is in pounds/mole
-------
Table A-8
LABORATORY ANALYSIS
Run 12
Percent
Composition
Water
Ash
Acid Insol-
uble Ash
Volatiles
Carbon
Hydrogen
OO
bo Nitrogen
Oxygen
f
Heating Value
Test
1
6.17
1.12
0.23
-
46.6
5.9
0.2
43.5
7715
Feed
Test
2
6.18
1.05
0.24
-
46.4
5.7
0.4
39.3
7663
Average
6.18
1.09
0.24
-
~~~
46.5
5.8
0.3
41.4
7689
Test
1
2.37
7.41
2.41
21.99
81.6
2.4
0.3
17.7
12,429
Char
Test
2
2.37
7.34
2.92
21.22
80.6
2.4
0.4
18.0
12,356
Oil
Test Test
Average 1 2 Average
2.37 56.9 - 56.9
7.37 -
2.67 -
21.60 -
81.1 41.7 41.7 41.7
2.4 7.9 8.0 8.0
0.4 0.4 0.4 0.4
17.9 48.4 45.6 47.0
12.J93 20,000 19,400 16,600*
Off Gas
Non-
Condensible
Components
N2
CO
co2
H2
CH
t
C2
£.
C3
C,
4
•j-
Heating
Value
**
Molecular
Weight
Percent
39.5
16.2
21.7
10.2
4.76
0.29
0.06
2,010*
28.3
**
Heating value is in Btu/pound
These values of heating value were calculated from the elemental composition. They were used in the heat balance.
Molecular weight is in pounds/mole
-------
00
IjO
Table A-9
LABORATORY ANALYSIS
Run 13
Percent
Composition
Water
Ash
Acid Insol-
uble Ash
Volatiles
Carbon
Hydrogen
Nitrogen
Oxygen
.
Heating Value
Test
1
6.80
1.15
0.38
-
46.3
5.8
0.3
44.4
7592
Feed
Test
2
6.74
1.14
0.36
-
46.3
5.8
0.2
46.9
7654
Average
6.77
1.15
0.37
-
46.3
5.8
0.3
45.6
7623
Test
1
1.67
5.81
2.93
34.30
75.5
3.2
, 0.4
21.6
11,408
Char
Test
2
1.58
6.07
3.16
35.32
78.0
3.1
0.3
20.1
11,456
Oil
Test Test
Average 1 2 Average
1.63 60.5 63.6 62.1
5.94 - - -
3.05 -
34.81 -
76.8 44.7 45.2 44.9
3.2 8.4 9.4 8.4
0.4 0.8 0.7 0.8
20.9 46.1 45.8 45.9
11,432 16,200 9880 16,800*
Off
Non-
Condensible
Components
N2
CO
co2
H2
CH,
C.
C3
C4
f
Heating
Value
**
Molecular
Weight
Gas
Percent
42.8
14.7
19.0
9.2
5.2
0.25
0.02
-
2,050*
28.1
**
Heating value is in Btu/pound
*
These values of heating value were calculated from the elemental composition. They were used in the heat balance.
Molecular weight is in pounds/mole
-------
00
-p-
Table A-.10
LABORATORY ANALYSIS
Run 15
Percent
Composition
Water
Ash
Acid Insol-
uble Ash
Volatiles
Carbon
Hydrogen
Nitrogen
Oxygen
f
Heating Value
Test
1
3.14
0.75
0.31
-
48.6
5.9
0.1
46.3
7932
Feed
Test
2
3.74
0.76
0.33
-
48.2
5.9
0.3
45.2
8003
Average
3.44
0.76
0.32
-
48.4
5.9
0.2
45.8
7968
Test
1
1.27
3.71
2.35
42.84
70.4
3.7
0.3
27.4
11,125
Char
Test
2
1.09
3.76
2.33
43.30
71.0
4.1
0.4
27.0
11,030
Oil
Test Test
Average 1 2 Average
1.18 61.7 - 61.7
3.74 -
2.34 -
43.07 -
70.7 45.9 45.8 45.9
3.9 7.6 7.5 7.6
0.4 0.1 0.1 0.1
27.2 46.3 47.8 47.1
11,078 16,700 16,900 16,300*
Off
Non-
Condensible
Components
Y
CO
co2
Ho
2
CH
H
c.
£,
S
J
C4
*f
+
Heating
Value
**
Molecular
Weight
Gas
Percent
36.8
21.7
15.1
10.5
5.5
1.43
a. 39
0.13
3,020*
27.1
**
Heating value is in Btu/pound
it
These values of heating value were calculated from the elemental composition. They were used in the heat balance.
Molecular weight is in pounds/mole
-------
00
Table A-ll
LABORATORY ANALYSIS
Run 16
Percent
Composition
Water
Ash
Acid Insol-
uble Ash
Volatiles
Carbon
Hydrogen
Nitrogen
Oxygen
f
seating Value
Test
1
4.45
0.62
0.20
-
47.3
5.9
0.1
44.3
8117
Feed
Test
2
4.45
0.59
0.21
-
45.7
5.7
0.1
43.9
7986
Average
4.45
0.61
0.21
-
46.5
5.8
0.1
44.1
8052
Test
1
0.95
4.93
3.13
2.93
79.4
3.6
0.5
13.8
13,322
Char
Test
2
0.95
4.49
2.62
2.93
79.4
3.5
0.4
12.8
13,394
Oil
Test Test
Average 1 2 Average
0.95 49.7 - 49.7
4.71 -
2.88 -
2.93 -
79.4 42.1 40.0 41.1
3.6 7.9 6.3 7.1
0.5 0.1 0.8 0.5
13.3 47.2 46.8 47.0
13,358 - - 14,700*
Off
Non-
Condensible
Components
N2
CO
co2
H.
2
CH4
*t
c2
£.
C3
c.
4
f
Heating
Value
**
Molecular
Weight
Gas
Percent
44.1
21.2
14.1
12.7
4.11
1.02
0.13
2,530*
26.5
**
Heating value is in Btu/pound
These values of heating value were calculated from the elemental composition. They were used in the heat balance.
Molecular weight is in pounds/mole
-------
CO
Table A-12
LABORATORY ANALYSIS
Run 17
Percent
Composition
Water
Ash
Acid Insol-
uble Ash
Volatiles
Carbon
Hydrogen
Nitrogen
Oxygen
f
Heating Value
Test
1
3.92
0.71
0.20
-
48.6
5.9
0.1
46.1
7999
Feed
Test
2
3.57
0.73
0.22
-
47.8
5.5
0.1
42.0
8017
Average
3.74
0.72
0.21
-
48.2
5.7
0.1
44.0
8008
Test
1
1.16
7.46
5.37
49.20
63.6
4.4
0.2
27.1
10,024
Char
Test
2
1.09
7.25
5.40
49.99
62.8
4.4
0.1
27.1
9964
Oil
Test Test
Average 1 2 Average
1.13 74.1 - 74.1
7.36 - - -
5.39 -
49.60 -
63.2 46.0 44.7 45.4
4.4 7.4 8.2 7.8
0.2 0.8 0.7 0.8
27.1 46.2 48.2 47.2
9994 - - 16,300*
Off
Non-
Condensible
Components
N2
CO
CO
f.
H2
Z.
CH
*T
C2
C,
C4
f
Heating
Value
**
Molecular
Weight
Gas
Percent
47.9
15.3
19.3
12.6
5.30
0.87
0.25
-
1,960*
27.3
**
Heating value is in Btu/pound
*
These values of heating value were calculated from the elemental composition. They were used in the heat balance.
*
Molecular weight is in pounds/mole
-------
00
Table A-13
LABORATORY ANALYSIS
Run 18
Percent
Composition
Water
Ash
Acid Insol-
uble Ash
Volatiles
Carbon
Hydrogen
Nitrogen
Oxygen
.
Heating Value
Test
1
5.63
0.49
0.12
-
47.6
5.8
0.4
45.1
7802
Feed
Test
2
5.90
0.41
0.09
-
47.4
5.9
0.6
46.3
7791
Average
5.76
0.45
0.11
-
47.5
5.9
0.5
45.7
7797
Test
1
2.24
6.51
3.85
5.33
88.2
0.9
0.8
14.0
12,735
Char
Test
2
2.22
6.20
3.68
5.55
87.9
0.9
0.7
15.2
12,823
Oil
Test Test
Average 1 2 Average
2.23 64.7 - 64.7
6.36 -
3.77 - - -
5.44 -
88.1 50.7 44.4 47.7
0.9 7.4 5.6 6.5
0.8 0.3 0.8 0.6
14.6 43.6 47.3 45.5
12,779 - - 15,200*
Off
Non-
Condensible
Components
N2
CO
co2
H2
CH,
C2
C3
C4
f
Heating
Value
**
Molecular
Weight
Gas
Percent
47.4
22.2
13.4
11.4
4.84
0.78
0.13
-
2,720*
26.6
Heating value is in Btu/pound
These values of heating value were calculated froit the elemental composition. They were used in the heat balance.
**
Molecular weight is.in pounds/mole
-------
00
00
Table A-14
LABORATORY ANALYSIS
Run 19
Percent
Composition
Water
Ash
Acid Insol-
uble Ash
Volatiles
Carbon
Hydrogen
Nitrogen
Oxygen
j.
Heating Value
Test
1
7.29
0.48
0.21
—
45.4
5.5
0.5
44.8
7718
Feed
Test
2
7.41
0.46
0.19
—
46.1
5.7
0.7
45.0
7712
Average
7.35
0.47
0.20
-
45.8
5.6
0.6
44.9
7715
Test
1
2.20
4.54
2.96
36.71
84.1
3.7
0.5
13.3
10,713
Char
Test
2
2.13
4.99
3.41
37.56
83.2
3.4
0.5
14.7
10,709
Oil
Test Test
Average 1 2 Average
2.17 69.8 - 69.8
4.77 -
3.19 -
37.14 - -
83.7 54.5 57.2 55.9
3.6 6.8 6.9 6.9
0.5 0.9 0.9 0.9
14.0 36.8 38.2 37.5
10,711 - - 16,000*
Off Gas
Non-
Condensible
Components
N2
CO
CO
£»
H
£.
CH
H
C2
f~
c.
J
C.
4
f
Heating
Value
**
Molecular
Weight
Percent
51.4
19.4
15.2
14.3
4 04
H1 • w*f
1.07
0 24
\J • ^*T
2,370*
26.4
**
Heating value is in Btu/pound
*
These values of heating value were calculated from the elemental composition. They were used in the heat balance.
Molecular weight is in pounds/mole
-------
CO
VO
TABLE A-15
TRACE ELEMENT ANALYSES
Run
Type
Percent Composition
Number Sample Cr
Co
Cu
Fe
Mn
Ni
Zn
Feed .005
Char .017
Oil .0017
15 Feed .007
15
.004 .010
.002 .005
Oil .0017
.39 .10
.008 .024
.29
.016 .028 3.12 .61
.022 .060 .90
.26 .14
15 Char .022 .005 .017 1.98 .47
.008 .035 .09
.012 .042 .38
.0005 1.01 .0036 .0002 .003
.010
Cl
.0096 .307
.0061 .354
.0004 .57 .0022 .00008 .005 .008 .002 .0071
.0054 .136
.0061 .108
.0047 .0064
-------
1000
900
800
700
600
500
400
300
200
0)
a
o
£ioo
« 90
8 80
•3 70
>
60
50
40
30
20
10
10 20 40 60 80 100
Temperature (°C)
Figure A-l
Viscosity of Pine Waste Pyrolysis Oil
200
90
-------
100 I-
75|-
CO
CO
60 '
•S3 so -
-------
APPENDIX B
SAMPLE CALCULATIONS OF CHEMICAL, MASS AND
ENERGY BALANCES USED TO REDUCE TEST DATA
This appendix presents a sample calculation of the chemical, mass and
energy balances used to reduce the test data for run 7. The mass
balance follows the procedure presented in Figure 18. The energy
balance is based on the results of the mass balance and, is relatively
straightforward.
MASS BALANCE
Input
Laboratory Analyses -
Feed material (as run).
Composition Percent (wt)
C 45.7
H, 5.6
C 0.8
0^ (difference) 42.5
Moisture 5.4
Process Air
Composition Percent (Vol)
N9 79
°2 21
Composition -
Basis 100 pounds dry sawdust processed.
92
-------
Composition
Weight (Ib)
Sawdust
Process Air
Moisture
Total
100
55.8
5.75
162
Output
Laboratory Analysis -
Char
Composition
C
H
0_ (difference)
Moisture
Oil
Composition
C
H
0- (difference)
Moisture
Gas
Percent (wt)
86.9
5.7
0.6
6.8
1.11
Percent (wt)
44
7.48
0.93
47.6
66.5
Composition
N2
CO
co2
H2
CH,
Percent Volume
38.6
25.6
14.8
13.2
4.82
.81
.13
.02
Corrected to 100%
Volume
39.4
26.1
15.1
13.5
4.93
.81
.13
.02
93
-------
Composition -
Basis 100 pounds dry sawdust processed.
Char; Using a moisture content of 1.11 percent; the
amount of water and dry char in the 16.3 pounds
of recovered char was calculated:
Analyses
16. 3 (mixture) x (1 - .0111)
clar
ID mix
) = 16.1 Ib (char)
Ib HO
16. 3 (mixture) x .0111 (
- .2 Ib (H20)
Oil; The oil was collected and weighed. The amount
of dry oil was determined from the lower** of
a laboratory determination using the Dean-Stark
method or the calculated amount using CHNO analysis.
Equivalent Analysis
% (wt) Molecular Wt mols mols Water %
c
H2
N2
°2
isture
44
7.48 2
.93
47.6 32
44.0-
3.74 3.74 1.52
.93
1.49 2.98 0
53.6
The amount of H.,0 from Dean-Stark method was 66.5 percent, therefore
the smaller amount was selected or 53.6 percent.
Using this value the amount of dry oil and the amount of water in the
recovered 21.8 pounds of oil-water mixture was calculated.
21.8 Ib (mixture) x (1 - .536)
Ib mix'
Ib HO
21.8 Ib (mixture) x .536 (•
Ib
= 10.1 (Ib oil)
H2°>
Off-Gas -
From the analysis, the molecular weight of the off-gas was calculated:
**The lower value is taken because the oil cannot have any more water
than that associated with the oxygen from the CHNO analysis.
94
-------
Analysis Corrected
Composition to 100 Percent Molecular Weight
N2
CO
co2
H2
CH4
C2
C3
C4
39.4
26.1
15.1
13.5
4.93
.83
.13
.02
100 %
or mols
X
X
X
X
X
X
X
X
28
28
44
2
16
30
44
58
1100
731
664
27.0
79
25
6
1
2630 Ib
Average Molecular weight = • >> .. =26.3 Ib/mol
100 mols
To determine the total amount of off-gas produced (per 100 pounds of
sawdust) a nitrogen balance was made:
Total nitrogen input (from process air):
1 M • Mols N?
55.8 Ib(air) x — (M°^ air) x .79 (Mn, n,J = 1.52 (mols
Mols of off-gas
1.52 (mols N )
mols N
.394
3.85 mols off-gas
mol off-gas
Total weight of off-gas is:
3.85 (mols) x 26.3 (-% = 102 Ib (off-gas)
mol
Water: The amount of water in the off-gas was determined
by a hydrogen balance.
95
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Input H
Sawdust 5,9
H20 .64 (lbH2)
6.54 (lbH2)
Output H.
Char: 16.3 (.057) = .93 Ib H,
Oil: 21.8 (.0748) = 1.63 Ib H^
off-gas
mol
H,
z
CH4
C2
C3
C4
H
mol off-gas
.135
.0986
.0249
.0052
.001
.2647 Total mols Hn
/
mol off-gas
mols H .
.2647 (—: jrj ) x 3.85 (mol off-gas) x 2 —^7- = 2.04 lb H0
mols off-gas mols 2
Total output = 4.60 lb H2
Input - Output = lb H2 associated with water in off-gas
6.54 lb H - 4.60 lb H = 1.94 lb H
1 1 mol HO 18 lb HO
1.94 lb H. x 4 ?S „ 2 X -. r-rr^ x r-ir^r = 17.5 lb HO0
2 2 lb H2 1 mol H2 1 mol H20 2
Total water is the sum of water in off-gas, oil and char:
17.5 + 11.1 + .2 = 28.8 lb H20
The total mass accounted for in the output is the sum of the char, oil,
off-gas, and water:
96
-------
16.1 + 10.1 + 102 + 28.8 = 157
Oxygen Balance; An oxygen balance was made as a check on the amount
of water in the off-gas.
Input;
Sawdust;
lb 0
100 (lb sawdust) x .425 (lb sawdust) =42.5 (lb 02)
Water in feed;
5.75 lb H.O is equivalent to 5.1 lb 0,
£• &*
Process Air:
, , . mol 0 lb 0,
ee o it. • 1 /mo is air. on .2 00
55.8 lb air x ^ ( lb ) x .21 —- x 32
= 12.9 lb 02
Total input; 42.5 + 5.1 + 12.9 = 60.5
Output;
Char; (including associated moisture)
16'3 lb X '°68 () * 1'11 lb °
Oil; (including associated moisture)
lb 0
21.8 lb x .476 (-rv—=7) = 10.4 lb 00
lb oil 2.
Water; (not in oil or char)
14-8 lb x -889 ' = 13-2 lb
Off-Gas; (dry)
mols 00
mols off-gas
CO .1305
C0n .151
,total mols OQN
mols off-gas
97
-------
mols 02 32 lh
.2815 — TJ x 3.85 (mols off-gas) x —-,—•:^- = 34.7 Ib 0,,
mols off-gas v 6 mols 0 2
Total output 0 is the sum of the amounts from char, oil, water and
off-gas. The amount unaccounted for is the difference between input and
output:
60.5 - 59.4 = 1.1 Ib 02
A carbon balance was made to account for oil lost due to inefficiency
of the condenser and some leakage in the system.
Input:
Sawdust: 100 Ib x .482 Ib C = 48.2 Ib C
Output;
Char: 16.3 x .869 = 14.2 Ib C
Oil: 21.8 x .440 = 9.59 Ib C
Off-Gas; From off-gas analysis the amount of carbon in the gas
is calculated:
mo 1 s 0
Composition -ols of -£
CO .261
C02 .151
CH. .0/49
4
C2 .017
C3 .004
C4 ,001.
. „,, ..total mols C-.
. 4o J ( — • ; -- jr? -- )
mol off-gas
, _„ mols C oor-i ee 12 Ib C 10 i 11- /••
.483 — :; — rr - x 3.85 mols off-gas x --- r— — - = 22.3 Ib C
mol off-gas mol C
The total output of carbon is the sum of the carbon in the char, oil,
and off-gas:
14.2 + 9.59 + 22.3 = 46.1 Ib
The difference between the input and output represents the "lost carbon."
48.2 - 46.1 = 2.1 pounds
98
-------
Total output, then is the sum of the char, oil, off-gas, water and lost
carbon.
16.1 Ib char + 10.1 Ib oil + 102 Ib off-gas + 28.8 Ib HO
+ 2.1 Ib "lost" carbon = 159 Ib
The amount of mass unaccounted for = 162 - 159 = 3 Ib.
The percentage mass balance error is
3
162
x 100 = 1.9%
ENERGY BALANCE
Basis: 100 pounds dry sawdust, reference: 70°F, off-gas temperature:
300°F, char temperature: 1101°F, ATcooling water - 10°F.
Input
From laboratory data the heating value of dry sawdust feed is 8139
Btu/lb. Therefore the total heat was obtained by:
100 Ib x 8139 Btu/lb = 914,000 Btu
Output
From the mass balance 16.1 Ib char, 10.7 Ib of oil, 102 Ib of off-gas,
and 28.8 Ib of water were produced.
The.heating value of the char was determined directly in the laboratory
to be 13,400 Btu/lb. The heating value of the oil and the off-gas was
calculated from the constituent determinations to be 16,300 Btu/lb and
2820 Btu/lb respectively. The heat content of the water was determined
from the steam tables. Then the chemical energy was obtained by
multiplying the heating value of the product times the weight produced.
16.1 Ib char x 13,400 Btu/lb = 216,000 Btu
10.7 Ib oil x 16,300 Btu/lb = 172,000 Btu
102 Ib off-gas x 2820 Btu/lb = 288,000 Btu
2.1 Ib "lost" carbon x 14,500 Btu/lb = 30,500 Btu
Latent and sensible energy was calculated from the data as follows:
28.8 Ib (water) x 1142 Btu/lb = 32,900 Btu
102 Ib (off-gas) x .2 Btu/lb °F x (300°F - 70°F) = 4690 Btu
16.1 Ib (char) x 3 Btu/lb °F x (1101 °F - 70°F) = 4980 Btu
10.7 Ib (oil) x 200 Btu/lb = 2140 Btu
99
-------
Heat lost in cooling air tubes:
2008 Ib x 1 Btu/lb °F x 10°F = 20,000 Btu.
The convective loss from the system was estimated to be:
100 ft2 (1) Btu/ft2°F x 650°F = 6500 Btu
The total output energy is the sum of all these energies which is equal
to 778,000 Btu. Therefore:
Input Energy - Output Energy = 814,000 - 778,000 = 36,000 Btu
Percentage error in Energy Balance is
36,000
814,000
100
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APPENDIX C
ECONOMIC ANALYSIS
SAMPLE CALCULATION FOR A 100 TON/DAY UNIT
WORKING 24 HOURS A DAY INCLUDING DISPOSAL CHARGE
Inputs;
a. The capacity of the unit is 100 ton/day dry sawdust
b. The unit is in operation 24 hr/day 250 days/year
c. Fuel is worth $35 per ton
d. Interest rate is 9.5 percent
e. Depreciation of the unit is 10 years
f. Raw wastes are 50 percent moisture
g. Disposal charge is $3.00/ton of wet sawdust
h. The results apply to a medium size sawmill
i. 45.6 percent charcoal and oil can be obtained from the
dry sawdust
Utilization Factor;
Utilization factor (n) is the ratio between the production time and
the total time.
Total Time includes:
a. Production time (PT), which is the average time in which the
unit operates at each sawmill. This is found by dividing the
amount of sawdust that a medium size sawmill produces by the
capacity of the unit.
b. Starting time (ST), which is the average time interval from
arrival at the sawmill to the time the unit operates.
c. Turn-off time (TOT), which is the average time interval between
the time the unit stops and the time that the unit is back on
the road.
d. Traveling time (D/v), which is the average time that it takes
to travel from one sawmill to another. It is found by dividing
the average distance between two sawmills (D) by the average
speed that the unit travels (v).
101
-------
so:
= FT
11 PT + ST + TOT + D/v
The total of starting time, turn-off time and traveling time is
approximately two days in Georgia.
so:
ST + TOT + D/v =2
and:
PT
n =
PT + 2
Production time (PT) is the production rate of sawdust per year divided
by the capacity of the unit (CAP).
n =
PR
CAP PR
CAP
+ 2 PR + 2 x CAP
or:
Average production of a sawmill per year (TONS)
utilization factor = capacity of x time interval + Average production
the unit between turning of a sawmill per
(ton/day) off the unit year (ton)
and starting it
again at the
next sawmill (day)
The production rate of sawdust by a medium size sawmill is approximately
3,000 ton/year.
So the utilization factor for a 200 ton/day unit is:
3000
200 x 2 + 3000
. QQ
°'89
102
-------
Income;
The income per year, including disposal charge, is a function of:
capacity of the unit, number of shifts a day that the unit operates, the
amount of oil and charcoal that can be obtained from the dry sawdust,
utilization factor, number of days per year that the unit operates,
and the value of the fuel.
Income
year
Income
year
Capacity of Utilization Number working percent charcoal
the unit X factor X days per year X and oil obtained
dry ton/day
x price of fuel
from the dry
sawdust
capacity of number disposal utilization
x
the unit wet working charge
ton/day days
per year
100 -^ x 0.89 x 250 (days) x ^:°/0 x 35
,JL.,
200
,.
factor
ton
day
x 0.89 x 250 (days) x 3 (-*-) | = $488,610 per year.
Costs;
The different costs of the unit per year are: labor, overhead,
depreciation, interest and maintenance.
First shift group: includes one worker who earns $15,000 per year. He
is the foreman of the whole crew. There is also a helper who earns
$7,500 per year.
Second and third shift group: includes one worker who earns $12,000
pear year. He is the leadman of the shift. There is also a helper
who earns $7,500 per year.
Driver: one driver for each shift who earns $12,000 per year and serves
four units.
Overhead: overhead for each unit is $12,000 per year. It covers cost
at the headquarters for a manager, secretary and office space. Such an
office headquarters serves ten units or more.
Depreciation: depreciation cost assumes the life time of the unit to be
10 years with no value afterwards. The interest rate is nine and one-half
percent payable over 10 years. The cost of the unit as a function of
capacity is found by using the relation
1/2
Cost of Unit = 40,500 (capacity)
103
-------
The cost of a 100 ton/day unit is then $405,000.
The annual payment for the unit is $64,504.
The maintenance cost is $11,000 per year. It includes cost of parts
to be changed and covers the cost of a maintenance crew that services
four units. The total operating cost for a 100 ton/day unit is
$158,004 per year.
Net Income;
The net income not including tax is the difference between the total
income and the total cost,
so:
Net Income = $488 610 _ $158,004 = $330,600 per year
per year ' r
104
-------
English
Unit
Btu
Cfm
ft
°F
hp
hr
inch
inch of
Ib
minute
psig
ton
multiply by
multiply by
multiply by
subtract 32
multiply by
multiply by
multiply by
water multiply by
multiply by
multiply by
multiply by
multiply by
APPENDIX D
UNIT CONVERSION TABLE
Conversion
1.055 X 103 to obtain
4.72 X 10 to obtain
_i
3.048 X 10 to obtain
and divide by 1.8 to obtain
7.457 X 102 to obtain
3600 to obtain
2.54 X 10~2 to obtain
2.458 X 10~3 to obtain
4.536 X 10"1 to obtain
60 to obtain
6.804 X 10~ to obtain
9.0718 X 102 to obtain
Metric
Unit
joules
3
meters /sec
meters
°C
watts
seconds
meters
atmospheres
kilogram
seconds
atmospheres
kilogram
105
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-76-090
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Clean Fuels from Agricultural and Forestry Wastes
5. REPORT DATE
April 1976
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
J.W. Tatom, A.R. Colcord, J. A. Knight,
and L.W. Elston
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Engineering Experiment Station
Georgia Institute of Technology
Atlanta, Georgia 30332
10. PROGRAM ELEMENT NO.
1AB013: ROAP BJV-012
11. CONTRACT/GRANT NO.
68-02-1485
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final; 6/74-3/75
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTES Project officer for this report is J.D. Kilgroe, Mail Drop 61,
Ext 2851.
16. ABSTRACT
r6port gives results of an experimental investigation of the operating-
parameters for a mobile waste conversion system based on the Georgia Tech
Engineering Experiment Station's partial oxidation pyrolysis process. The object
of the testing was to determine the combination of parameters producing the most
char and oil and the least gas from agricultural and forestry wastes. The tests
indicated both the dominant influence of air/feed on char and oil yields , and the
desirability of low values of this ratio. In addition to the testing, a preliminary
design of a 200 ton/day mobile pyrolysis system for conversion of agricultural and
forestry wastes into clean fuels was made and a simplified economic analysis con-
ducted. The results of this work indicate the technical feasibility and the economic
profitability of such a system.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Air Pollution
Agricultural Wastes
Forestry
Wastes
Waste Treatment
Oxidation
Pyrolysis
Oils
Economic An-
alysis
Air Pollution Control
Clean Fuels
Forestry Wastes
Waste Conversion
Char
13B
02A
02F
07D
11H
05C
07B,07C
13. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
105
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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