EPA
United States
Environmental Protection
Agency
Office of Research and
Development
Washington, DC 20460
EPA/600/R-93/165
September 1993
Evaluation of an
Automated Sorting
Process for
Post-Consumer Mixed
Plastic Containers
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EPA/600/R-93/165
September 1993
EVALUATION OF AN AUTOMATED SORTING PROCESS
FOR POST-CONSUMER MIXED PLASTIC CONTAINERS
by
David V. Bubenick
Charles N. Faulstich, Jr.
wTe Corporation
Bedford, MA 01730
and
Solid Waste Association of North America
Silver Spring, Maryland 20910
Cooperative Agreement No. 818238
Project Officer
Diana R. Kirk
Waste Minimization, Destruction, and Disposal Research Division
Risk Reduction Engineering Laboratory
Cincinnati, Ohio 45268
RISK REDUCTION ENGINEERING RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OH 45268
Printed on Recycled Paper
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DISCLAIMER
The information in this document has been funded wholly or in part by the United States
Environmental Protection Agency under assistance agreement CR-818238 to the Solid Waste
Association of North America (SWANA). It has been subject to the Agency's peer and administrative
review and has been approved for publication as an EPA document. Mention of trade names or
commercial products does not constitute endorsement or recommendation for use.
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FOREWORD
Today's rapidly developing and changing technologies and industrial products and practices
frequently carry with them the increased generation of materials that, if improperly dealt with, can
threaten both public health and the environment. The U.S. Environmental Protection Agency is charged
by Congress with protecting the Nation's land, air, and water resources. Under a mandate of national
environmental laws, the agency strives to formulate and implement actions leading to a compatible
balance between human activities and the ability of natural systems to support and nurture life. These
laws direct the EPA to perform research to define our environmental problems, measure the impacts,
and search for solutions.
The Risk Reduction Engineering Laboratory is responsible for planning, implementing, and
managing research, development and demonstration programs to provide an authoritative, defensible
engineering basis in support of the policies, programs, and regulations of the EPA with respect to
drinking water, wastewater, pesticides, toxic substances, solid and hazardous wastes, and
Superfund-related activities. This publication is one of the products of that research and provides a vital
communication link between the researcher and the user community.
This publication is part of a series of publications for the Municipal Solid Waste Innovative
Technology Evaluation (MITE) Program. The purpose of the MITE program is to: 1) accelerate the
commercialization and development of innovative technologies for solid waste management and
recycling, and 2) provide objective information on developing technologies to solid waste managers, the
public sector, and the waste management industry.
E. Timothy Oppelt
Risk Reduction Engineering Laboratory
in
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PREFACE
The Municipal Solid Waste Innovative Technology Evaluation (MITE) Program is managed by
the U.S. Environmental Protection Agency (EPA) Office of Research and Development (ORD). The
purpose of the MITE program is to: 1) accelerate the commercialization and development of innovative
technologies and programs for solid waste management and recycling, and 2) provide objective
environmental and cost information on developing technologies and programs to solid waste managers
in the public and private sectors.
These goals are met by selecting, through a competitive process, technologies and programs
whose sponsors have submitted proposals to EPA through its annual solicitation. The proposals are
reviewed and the most promising projects are selected for inclusion in the program. Once selected,
EPA, with the cooperation of the technology developer, formulates an evaluation plan which emphasizes
the costs, effectiveness and environmental impacts of the technology. Each project consists of a field
demonstration and an associated evaluation. The MITE program is administered by the Solid Waste
Association of North America (SWANA). SWANA coordinates an Advisory Committee review as well as
assisting in the formulation of the evaluation plans.
The technology developer, the Rutgers University Center for Plastics Recycling Research,
conducted this demonstration. wTe Corporation conducted the on-site performance evaluation, analyzed
the data collected, and prepared the subject report.
A limited number of copies of this report will be available at no charge from EPA's Center for
Environmental Research Information, 26 West Martin Luther King Drive, Cincinnati, Ohio 45268.
Requests should include the EPA document number found on the report's cover. When the supply is
exhausted, additional copies can be purchased from the National Technical Information Service,
Ravensworth Building, Springfield, Virginia 22161 (telephone number - 703-487-4600).
IV
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ABSTRACT
This project evaluates a proof-of-concept, pilot-scale, automated sorting system for mixed
post-consumer plastic containers developed by the Rutgers University Center for Plastics Recycling
Research (CPRR). The study qualifies the system's ability to identify and separately recover five types
of plastic containers representative of those found in plastics recycling programs. It also addresses the
system's potential for full-scale commercial application.
Three series of tests were performed: single composition, short-term tests; mixed composition,
short-term tests; and mixed composition, extended tests. A total of 82 test runs were performed during
which 66,632 bottles were processed.
The five bottle types considered were natural HOPE, PVC, clear PET, green PET, and opaque
HOPE. The containers recovered at each product collection station were counted and the results
compared to pre-established recovery goals. Bottle counts were then converted to weight recoveries
using average bottle weights. The resulting product purity/contamination weight percents were
compared to allowable product contamination limits representative of industry practice. From a detailed
video tape analysis of a representative test, an exact profile of bottle feed timing and sequence was
reconstructed. This analysis provided valuable insight into system feed and transport dynamics as well
as an understanding of how product contamination occurs.
The system produced statistically reproducible results and proved to be mechanically reliable.
However, it failed to achieve all of the commercial level container recovery and product contamination
limit goals. It was concluded that bottle singulation and spacing greatly influenced the effectiveness of
the identification/separation equipment.
This work was submitted by wTe Corporation in fulfillment of Contract No. 850-1291-4. The
contract was administered by the Solid Waste Association of North America and sponsored by the U.S.
Environmental Protection Agency. This report covers a period from May, 1992 to July, 1993.
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CONTENTS
Foreword
Preface
Abstract
Figures
Tables
Acknowledgments
1. Introduction
Background
Project overview
Technology status
2. Conclusions/Recommendations
Conclusions
Recommendations
3. System Description
4. Testing Methodology
Project objectives
Quality assurance objectives
Feed material
Product contamination
Tests performed
Single composition tests
Mixed composition, short-term tests
Mixed composition extended tests
Determination of bottle feed rate
Data reduction, calculation, and validation methods
Test procedures and QA checks
Procedures common to all tests
Procedures specific to single composition tests
Procedures specific to mixed composition tests
Data validation
5. Test Results
Single composition tests
Single composition bottle recovery, percent of
bottles fed
Single composition bottle recovery, percent of
bottles presented
Single composition test bottle feed rates
Mixed composition, short-term tests
Bottle recovery, percent of bottles fed
Bottle recovery, percent of bottles presented
Product composition
Equipment failure/downtime
HI
iv
v
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ix
x
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35
35
VI
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CONTENTS (CONTINUED)
Mixed composition, extended 2,000 bottle tests 38
Mixed composition, extended test results 38
Bottle recovery, percent of bottles fed 38
Bottle recovery, percent of bottles presented 38
Product composition 39
Recovery mistakes 41
Unfed bottles 41
Equipment failure/downtime 43
Bottle delivery and clear PET station recovery analysis 43
Delivery sequence and timing 43
Qlear PET station mistakes 45
Types of identification/separation mistakes 46
6. Commercial Potential 49
Pilot system design comments and suggested modifications 49
Equipment cost estimate 52
Existing commercial systems 53
Magnetic Separation Systems, Inc. - BottleSort System 53
National Recovery Technologies, Inc. - VinylCycle System 54
Automation Industrial Control - PolySort System 54
References 55
Appendices - Mixed Composition 2,000 Bottle Extended Tests
A. Test Data As Collected 56
B. Extended Test Results, Outliers Not Included 63
C. Bottle Counts And Weight Percentages 69
Glossary of Terms 74
VII
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FIGURES
Number
1 Process flow diagram
2 Equipment layout
3 Feed bin, infeed conveyor, and oversize discharge chute
4 Infeed arrangement viewed from C4/C5 transition
5 Dual discharge chutes and underside of infeed conveyor
6 Conveyors C4b, C4c, C5, and C6
7 Green PET, clear PET, and PVC identification/separation stations
8 PVC and clear PET product chutes, conveyor C7 in foreground
Page
7
8
9
9
10
10
11
11
viii
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TABLES
1 Conveyor schedule
2 Typical mixed plastics compositions
3 Assumed product contamination limits
4 Tests performed
5 Test data as collected
6 PVC data calculations
7 Bottle counts and weight percentages
8 Bottle recoveries based on bottles fed into the system, single composition tests
9 Bottle recoveries based on bottles presented to each station, single
composition tests
10 Bottle recoveries based on bottles fed into the system, mixed composition,
short-term tests
11 Bottle recoveries based on bottles presented to each station, mixed
composition, short-term tests
12 Comparison of single and mixed composition short-term test effective feed
rates for maximum recoveries based on bottles presented to each station
13 Average product components, mixed composition, short-term tests
14 Bottle recoveries and effective feed rates based on bottles fed into system,
extended tests
15 Bottle recoveries and effective feed rates based on bottles presented to
each station, extended tests
16 Average product compositions, extended tests
17 Comparison of mistake distribution to feed mix proportions, extended tests
18 Error frequency, extended tests
19 Unfed bottles, extended tests
20 Comparison of video vs field bottle count, extended tests
21 Bottle separation distances
22 Bottle delivery rates, extended tests
23 Bottle delivery/recovery errors, clear PET station only
24 Minimum separation distances for each bottle presented to clear PET station
25 Equipment Costs
12
16
18
19
23
24
26
30
31
33
34
35
36
38
39
40
41
42
42
44
44
45
47
48
53
IX
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ACKNOWLEDGMENTS
This project was funded under the U. S. EPA's Municipal Innovative Technologies Evaluation
(MITE) Program. Project management was provided by the Solid Waste Association of North America
(SWANA). The EPA Project Coordinator was Diana Kirk, and SWANA's Project Officer was Charlotte
Frola.
The principal system developers were Henry Frankel, Jose Fernandes, and Sergey
Miroshnichenko of the Rutgers University Center for Plastics Recycling Research.
wTe Corporation evaluated the technology and prepared the report. The principal authors were
Charles Faulstich and David Bubenick, who also served as wTe's Program Manager. Report reviewers
included Diana Kirk and Lynnann Hitchens of the U. S. EPA, Charlotte Frola of SWANA, Aarne Vesilind
of Duke University and James Abert, consultant.
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SECTION 1
INTRODUCTION
BACKGROUND
The significant differences in plastic resin properties require that post-consumer plastic
containers be separated by resin type before they can be processed into a form that can be used as a
substitute for virgin resin. Until recently, manual sorting has been the only method commercially
available for accomplishing this separation. Manual sorting has been found to be less than ideal,
however, owing to high labor and training expenses and its susceptibility to error. While some
identification/separation errors involving polyethylene terephthalate (PET) and high density polyethylene
(HOPE) can be tolerated, very few such errors involving polyvinyl chloride (PVC) can be tolerated due to
the physical/chemical incompatibility of PVC with PET. Compounding the manual separation problem is
the visual similarity of some PVC and PET bottles.
Automated sorting systems are the latest technological development for the recycling of
post-consumer plastic containers. These systems hold the promise of fast, cost-effective, and accurate
resin separation from a mixed plastic container feed stream. The pilot automated sortation system for
mixed post-consumer plastic containers developed by the Rutgers University Center for Plastics
Recycling Research (CPRR) is one of the first such systems developed during the past few years, and is
believed to be the first system to be rigorously tested by an independent party.
The Rutgers system integrates equipment that separates whole, uncrushed, mixed rigid plastic
containers into the five most common household plastic bottle types: PVC, clear PET, green PET,
natural HOPE, and opaque HOPE. A bottle presentation subsystem and an identification/separation
subsystem comprise the overall system. The bottle presentation subsystem incorporates material
handling equipment for the purpose of presenting the bottles to the identification/separation subsystem in
an orderly and uniform manner, with each container separate and distinct from its predecessor and from
its follower. The identification/separation subsystem consists of equipment for selectively identifying and
removing bottles from the feed stream.
The system uses various techniques to perform the identification and separation of plastic
containers. First, oversize containers consisting predominantly of natural HOPE milk and water jugs are
removed by mechanical means. X-ray fluorescence is then used to identify the chlorine atom-containing
bottles, namely PVC, and air jets force the detected containers away from the flow stream. Optical
sensors then detect the transparent clear and green PET bottles which are also removed from the flow
stream by air jets. The remaining containers consist primarily of opaque HOPE bottles which are
collected at the end of the presentation subsystem.
PROJECT OVERVIEW
Three series of tests were performed in order to evaluate the Rutgers CPRR system, as
described in the detailed Quality Assurance (QA) Plan prepared specifically for this projectW. Single
composition, short-term tests were performed in order to evaluate the recovery of each of the five
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container types without interference from containers of a different type. Mixed composition, short-term
tests were performed in order to evaluate the effectiveness of separating containers by type from a
mixed stream of known composition; to collect reliability, availability and maintainability (RAM) data; and
to establish the operating conditions for the third test series, the mixed composition, extended tests.
Finally, mixed composition, extended tests were run in order to evaluate the system performance over a
longer operating period, and to obtain additional RAM data to the extent permitted with a pilot scale
system. A total of 82 test runs were performed over two weeks of testing during which 66,632 bottles
were processed. Fifty tests were single composition tests; 17 were mixed composition, short-term tests;
and 15 tests involving approximately 2,000 bottles each comprised the extended mixed composition test
series.
The test procedure generally consisted of processing a known quantity and mixture of bottles
through the system, collecting the resulting products, and counting the bottles in each product to
determine the exact composition of each product. The numerical counts were compared to recovery
goals established in the QA Project Plan. These goals were: a recovery of 90 percent for natural HOPE,
opaque HOPE, clear PET and green PET; and a recovery of 100 percent for PVC. The numerical counts
were converted to weights using average bottle weights, and resulting product purity/contamination
values were calculated. These results were compared to the contamination limits generally established
in the Project QA Plan and later supplemented with data from industry practice.
Several test runs were video taped, and one of these runs was used to reconstruct an exact test
profile of the bottle feed timing and sequence. This analysis provided valuable insight into the dynamics
of the presentation subsystem and the nature of the recovery errors occurring at one representative
identification/separation station.
TECHNOLOGY STATUS
At the time of its development (1989 through 1991), the Rutgers CPRR system contained
state-of-the-art technology for PVC detection and innovative optical sensor technology for PET detection.
It was developed jointly by Rutgers University and the Asoma Instrument Company, the manufacturer of
the PVC identification equipment, with support from industry, academic and government sources. The
primary purpose of the Rutgers system was to demonstrate the PVC detection and optical sensor
technology at pilot scale. It therefore was designed to process bottles of round cross section and limited
size such as those used for soft drinks and edible oil. Inclusion of oversize bottle control allowed the
recovery of an oversize product, consisting of predominantly natural HOPE. Because the collection of
residuals is inherent in any conveyor system, it was possible to passively collect another product at the
end of the system, namely opaque HOPE.
The major emphasis during system development was on the detection and separation
technology, rather than on the material handling system. The feed system was constructed principally to
provide a means of delivering bottles of limited size and shape to the sensors at rates and mixtures
consistent with pilot-scale ffrodessing. No attempt was made to refine the feed system to deliver
containers at commercial-scale processing levels. This is unfortunate, because it is well recognized in
the industry that the limiting factor on the recovery accuracy of sorting systems is determined more by
the mechanical details of the material handling system than by the performance of the
identification/separation equipment. This axiom was generally supported by the results of this
investigation.
In weighing the results of this system evaluation, consideration must be given to the fact that the
Rutgers material handling system was not designed to deliver bottles at commercial-scale rates and in
commercial-scale mixtures. Thus, the CPRR system should not necessarily be viewed as a system with
direct commercial application.
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As one of the first automated systems developed, the Rutgers system uses the first generation of
Asoma PVC detection equipment, the XRF detector. A second generation PVC detection device, the
VS-2, has since been developed by Asoma. The VS-2 detector is mounted on the underside of a chute
over which the bottles are conveyed, rather than being mounted vertically as with the XRF detector. The
VS-2 arrangement eliminates the potential error inherent in the XRF detector caused by its sensitivity
loss with distance.
The VS-2 reportedly can identify PVC bottles anywhere over a 12-inch wide channel at a speed
of 10 feet per second and reportedly has a miss rate of less than one bottle in 100,000^. Asoma claims
that this detector is capable of a bottle detection rate of well over 100 bottles per second, but they
acknowledge that practical delivery rates are more in the range of 3 to 5 bottles per second. It was not
possible to incorporate this new technology into the Rutgers system prior to evaluating the system.
Therefore, the results of this investigation must be considered in light of the fact that the most advanced
PVC detection technology was not employed.
Several commercial systems have been developed simultaneously with and subsequent to the
development of the Rutgers system. These include the BottleSort System (Magnetic Separation
Systems), the VinylCycle System (National Recovery Technologies), and the PolySort System
(Automation Industrial Control). However, the recovery accuracy and throughput reported in the
literature for these systems have not been demonstrated in a rigorous testing program similar to that
described in this report on the Rutgers system. These commercial systems are briefly described in
Section 6.
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SECTION 2
CONCLUSIONS/RECOMMENDATIONS
Prior to this MITE evaluation, rigorous testing of the Rutgers system had never been performed
on mixed bottle feedstock at elevated feed rates. The emphasis during development of the system was
on the performance of the optical and X-ray fluorescence sensors. The material handling system was
constructed to deliver bottles in a manner consistent with pilot scale processing so that the sensors could
be tested. The goals established in the Project Quality Assurance Plan are more suited to a
commercial-scale system. Failure to meet the commercial-scale expectations does not necessarily
indicate that the pilot scale system developed by the CPRR cannot be upgraded to a successful
commercial scale system.
CONCLUSIONS
The individual unit operations employed in the Rutgers system were found to be reasonably
effective in reproducibly separating and recovering bottles by type from a mixed stream. However, as a
whole, the Rutgers system did not achieve the recovery and product purity goals established prior to
testing. The deficiencies of the material handling system and the lack of a state-of-the-art PVC detector
severely limited the performance of the overall system in terms of recovery and throughput. Exactly how
much system error was due to material handling and how much was due to equipment malfunction could
not be established.
The overall system was found to be capable of correctly recovering, with 95 percent confidence,
90.9 percent of the bottles fed during a 4.8-hour mixed composition extended test. The average bottle
feed rate was 74 bottles per minute, or 782 pounds per hour using average bottle weights. Of the five
products recovered in the extended test series, only natural HOPE and clear PET achieved their
respective recovery goals with 95 percent confidence. Only the opaque HOPE product met the
established contamination criteria. AH other products exceeded the contamination limits for at least one
other bottle type.
The material handling equipment exhibited several deficiencies that lowered the overall system
performance. For example, it could not deliver a consistently spaced mixed bottle stream to the
identification/separation equipment at an average feed rate of 74 bottles per minute. In some cases,
bottles were either too closely spaced or not properly aligned to allow them to be properly identified
and/or ejected. In many cases, the bottles were widely spaced, reducing the system throughput
considerably. Also, some components of the material handling system could not consistently
accommodate the range of bottle sizes, shapes and orientations encountered in the testing, as
evidenced by the large number of bottle jams observed.
Although no consistent correlation between bottle recovery and feed rate was observed, bottle to
bottle interference during mixed composition testing was found to negatively affect bottle recovery.
During the single composition tests, bottle recoveries were generally much higher than during the mixed
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composition testing despite much higher feed rates. As the system was designed to process only whole,
uncrushed bottles, only undamaged bottles were used in the evaluation. No determination of the
system's separation efficiency on crushed, dented, or heavily scratched bottles was made.
The video tape analysis of the clear PET station during one extended test showed that
approximately one-half of the bottle recovery mistakes occurred during the relatively short period of time
when bottles were spaced less than 2 inches apart. At this close spacing, the air jet separation
equipment could not selectively remove single bottles consistently. Approximately 8 percent of the
bottles were so spaced. The remaining mistakes, also approximately one-half of the total, are
attributable to presentation subsystem problems with bottle alignment and orientation, and
identification/separation subsystem errors due to non-optimal bottle size, shape, and condition.
RECOMMENDATIONS
The existing system was designed to pilot-scale standards and as such is not substantial enough
for the demands of long term commercial-scale operation. Certain components of the Rutgers system
are expected to require only minor redesign to improve throughput, container recovery accuracy, and
reliability, and to prevent feed jams. Other recommended changes are more significant in that they
substantially add to or change the basic process flow of the system. An example of this type of design
change is the incorporation of the Asoma VS-2 PVC sensor into the system to improve PVC recoveries
and therefore decrease PVC contamination. Also, a multiple pass system could improve recovery by
allowing more than one opportunity to detect and remove the target products. For example, additional
PVC sensors may be required to assist in the cleanup of certain product streams if primary PVC
recovery is insufficient to meet product purity requirements. Use of the new Asoma VS-2 sensor may at
least partially eliminate the need for secondary PVC cleanup, however. Re-design of the system to allow
bottle detection from below rather than from the side might allow the system to process crushed bottles.
The effectiveness of the air jets at removing crushed bottles is unknown, however, and a new separation
technique for crushed natural HOPE bottles would need to be developed.
Specific design recommendations are described in Section 6, Commercial Potential. The less
extensive modifications that improve the material handling aspects of the system may in themselves be
successful in raising system performance to acceptable commercial-scale levels. However, the degree
of improvement in performance resulting from any of the recommended equipment modifications cannot
be ascertained without additional testing.
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SECTION 3
SYSTEM DESCRIPTION
Figure 1 presents a flow diagram of the Rutgers system that separates, by type, a mixture of the
following rigid plastic containers: translucent or clear high density polyethylene (natural HOPE), polyvinyl
chloride (PVC), clear polyethylene teraphthalate (clear PET), green polyethylene teraphthalate (green
PET), and opaque high density polyethylene (opaque HOPE). Figure 2 presents a scale plan view of the
actual equipment layout, and Figures 3 through 8 are photographs of the system. The conveying system
is described in Table 1.
Gaylord boxes containing the bottle feedstock are manually emptied into a live bottom feed bin
(Figure 3). An inclined cleated belt conveyor (C2) draws the bottles out at a regulated rate. The live
bottom consists of a short conveyor (C1) controlled by a level sensor mounted on the feed bin wall.
When the bin level drops below the sensor level, the conveyor is activated, moving the feedstock pile
against the inclined drag conveyor.
A variable speed controller allows conveyor C2 to operate at any percentage of the maximum
speed from 0 to 100, and the container feed rate is controlled by adjusting this speed. The cleats on
conveyor C2 are 3-1/2 inches high, allowing only one layer of containers to be carried by the conveyor.
Burden depth and bottle alignment is automatically controlled by fallback caused by the conveyor's
inclination and by a leveling bar mounted inside the live bottom storage bin.
At the head end of conveyor C2, the first stage of a two-stage mechanical separation process
takes place; a counter-clockwise rotating paddle wheel mounted above the belt ejects oversize
containers into a chute. At the lower end of the chute, the second stage of mechanical separation
occurs. Another paddle or "kick" wheel is set at a height above the chute sufficient to eject bottles of a
size similar to that of one-gallon natural HOPE containers, while allowing containers that are smaller in
profile to pass. Ejected containers are diverted onto conveyor C6 (Figure 4), and a plow then diverts the
containers from the conveyor into gaylord boxes. Containers not ejected by the kick wheel are dropped
back into the feed bin and are fed again.
The containers that are discharged by conveyor C2 drop onto conveyor C3 through a dual
discharge chute (Figure 5). The two parallel chutes serve as the first step in singulating the feed.
Conveyor C3 is equipped with two flexible metal strips that first divert the containers against one side of
the conveyor, and then back to the original side. The intent of these strips is to assist in the aligning and
singulation of the containers. Conveyor C3 feeds a three section singulating conveyor system (C4a,
C4b, C4c). This conveyor system consists of three adjacent overlapping conveyor sections, each
section operating at a slightly higher speed than the previous section. A diagonal plow diverts the bottles
from one section to the adjacent section. The increasing speeds of the conveyor sections are designed
to draw each container apart from its follower. Conveyor section C4c discharges onto presentation
conveyor C5, which conveys the containers past the identification/separation stations.
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Conveyor C5 is axially inclined such that the containers are in contact with the lower edge
skirting of the conveyor as they move downstream (Figure 6). The X-ray fluorescence and optical
sensors are located along the lower edge skirting. A bank of three air jets is located at the beginning of
conveyor C5 to assist in directing the containers against the lower edge skirting. These air jets were
ineffective, and were eventually disconnected to conserve air pressure.
Container
Feed Bin
No
Oversize Station
Bottle Size Larger
Than Paddle Wheel
Opening?
Yes ^
Oversize Station
Bottle Size Larger
Than Kick Wheel
Opening?
Yes
No
PVC Station
Detect Chlorine Atom?
Yes ]
* [
Ejected to
PVC Product
No
Clear PET Station
Is Light Transmitted?
Yes
Ejected to Clear
PET Product
No
Ejected to Natural
HOPE Product
Green PET Station
Is Light Transmitted?
Yes
Ejected to Green
PET Product
I
No
[Opaque HOPE Product]
Figure 1. Process flow diagram.
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GREEN PET
STATION
CLEAR PET
STATION
PVC
STATION
DIVERTER
(TYP)
DUAL
FEED
CHUTES
GAYLORD
BOX
(TYP)
\ PLOW(TYP)
AIR NOZZLES
FEED BIN
OVERSIZE
STATION 1
PADDLE 1
WHEEL s
^- OVERSIZE
STATION
KICK
WHEEL
Figure 2. Equipment layout.
8
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10
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Figure 7. Green PET, clear PET, and PVC
identification/separation stations (left to right).
Figure 8. PVC and clear PET product chutes, conveyor C7 in
foreground with plows and gaylord boxes.
11
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TABLE 1. CONVEYOR SCHEDULE
Conveyor
Pulley
Width, Approx. Motor diameter,
inches length HP inches Comments
C1
C2
C3
C4a
24
36
18
12
t
4'-0" 1/2
8'-6" 1/2
10.-0- 2
3'-8" 1
4
4
4
6
Forms live bottom in feed bin
3-1/2" deep cleats, inclined at 60
degrees
Skirting reduces effective width to 10"
Common motor for C4a, C4b, an<
JC4c,
8 V-belts, inclined at 17 degrees
C4b
12
4'-2"
6 Common motor for C4a, C4b, and C4c,
8 V-belts, inclined at 17 degrees
C4c
12
2'-9"
6 Common motor for C4a, C4b, and C4c,
8 V-belts, inclined at 17 degrees
C5
12
20'-6"
N/A
Inclined at approximately 17 degrees,
motor size not available
C6
C7
12
18
2
2
Plow diverts bottles to gaylords
Plows divert bottles to gaylords
The identification/separation stations are positioned along conveyor C5 in the following
sequence: PVC, clear PET, and green PET (Figure 7). To identify and remove PVC bottles, X-ray
fluorescence is used to detect the chlorine atom found only in these containers. When detected, two air
nozzles deliver a blast of compressed air that forces the detected container off conveyor C5 and onto
conveyor C7. The air nozzles are aimed such that they create a concentrated pressure wave to cleanly
force the container off the presentation conveyor without imparting any spin to the bottle.
PET containers are detected by a technique based on the optical transmission of visible light.
The opposed mode sensing technique consists of light emitting diodes (LEDs) as sources and
phototransistors as receivers. In this technique, the LEDs point directly at the phototransmitters with the
bottles passing between the two. The bottles either absorb, reflect, or refract the light, diminishing the
intensity of the light falling on the phototransistor. If the intensity of the light detected at the receiver is
above a selected adjustable level, a digital signal is sent to the ejector solenoid.
12
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The light sources actually consist of a bank of three LEDs; two outer LEDs to detect the physical
presence of a container, and one center LED to sample a region of the bottle unobscured by a label or
basecup. The center LED at the clear PET station uses a red light, whereas the center LED at the green
PET station uses a green light. The red light is capable of being transmitted through clear PET but is
optically blocked by green PET. Hence, green PET will not be detected at the clear PET station. The
light emitted by the LED at the green PET station is transmitted through both clear and green PET, and
thus is incapable of distinguishing between the two colors. Thus, any missed clear PET will be detected
at the green PET station. Both clear and green PET optical stations are equipped with air jets similar to
those used in the PVC identification/separation station to move the detected containers from conveyor
C5 onto conveyor C7.
The plows on conveyor C7 divert the PVC and PET products into separate gaylord boxes (Figure
8). Containers not removed from conveyor C5 by the identification/separation stations are discharged off
the end of conveyor C5 into a gaylord container. This product will consist primarily of opaque HOPE
containers since they should pass through the system undetected.
The system was originally designed to collect all materials removed by the
identification/separation stations onto conveyors C6 and C7 for discharge into a common container. In
order to keep each product separate from one another during the testing, plows were installed on the
conveyors immediately downstream of each identification/separation station to divert each product into a
separate gaylord container. Modifications to the system were also made voluntarily by the project
developers in the interim between the first week of testing and the second week of testing. Two flexible
metal diverters were added along the upper skirting of conveyor C5 to direct the bottles against the
sensor side of the conveyor skirting. The air jets located in this position for this same purpose were
found to be ineffective and were de-activated to conserve air pressure. Also, the axial tilt of conveyor C5
was reduced slightly from its 17 degree slope. Prior to the start of the extended test series, the house
air pressure was increased from 100 to 130 psi, and the blast duration at each separation station was
decreased by approximately 20 percent.
13
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SECTION 4
TESTING METHODOLOGY
PROJECT OBJECTIVES
The project objectives initially envisioned were as follows:
Determination of the maximum container feed rate, with 95 percent confidence, that will
assure 90 percent recoveries for natural HOPE, opaque HOPE, clear PET, and green
PET, as well as 100 percent recovery of PVC, while meeting specified product
contamination levels.
Determination of the mechanical reliability, availability, and maintainability (RAM) of the
overall system
Projection of the performance and operating economics for a commercial scale system.
Early in the project, it was determined that there was little advantage to collecting RAM data for a
pilot scale system. The system was not designed and constructed according to commercial-scale
standards, and the test results demonstrated that the equipment failures that occurred were a direct
result of the pilot-scale quality of the equipment. No information was available on the operation and
maintenance history of the equipment, data that are essential for a RAM analysis to be meaningful.
Nonetheless, data were collected regarding equipment failures and problems; however, no major
conclusions could be drawn from these data.
Similarly, the requirement for major system changes in order to scale the system up to
commercial level (which is beyond the scope of this MITE evaluation) rendered a detailed economic
analysis of the capital and operating costs meaningless. Rather, recommendations are offered for
several process modifications that may prove successful in upgrading the system to commercial-scale
quality (see Section 6). As indicated earlier, such performance improvements can only be quantified
after extensive additional testing, and therefore, no commercial scale cost estimate can be offered.
However, in order to provide a baseline cost reference, as required in all MITE program technology
evaluations, an estimate of the material costs for the Rutgers system as designed is provided in Section
6 (see Table 25).
To satisfy the primary project objective, a series of three tests were conducted. Single
composition, short-term tests evaluated the recoveries of a specific type of container without any
Interference from other container types. Mixed composition, short-term tests evaluated the effectiveness
of the system in separating containers by type from a mixed stream and established the operating
conditions for the third test series, the mixed composition, extended tests. The mixed composition,
extended tests were conducted to verify the system's capability to operate over a longer period of time,
based on the operating conditions established in the mixed composition, short-term tests. Qualitative
RAM data were obtained to the extent that a pilot-scale system can permit a meaningful evaluation of
such data. Testing was conducted during the weeks of September 21,1992 and October 5,1992.
14
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QUALITY ASSURANCE OBJECTIVES
The quality assurance objectives, established prior to testing, were as follows:
Container Recovery: A minimum recovery of 90 percent for natural HOPE, clear PET,
green PET, and opaque HOPE, and 100 percent recovery of PVC based on containers
actually presented for inspection.
Container Recovery Accuracy: Bottle recoveries at the primary identification/separation
stations of sufficient accuracy such that other product contamination levels are below
typical industry contamination limits.
9 System Reliability: An overall system reliability of 90 percent.
» System Availability: An overall availability of 90 percent.
e Test Completeness: A minimum of 60 percent of the test replicates be judged valid.
This objective is applicable to all but the extended tests.
Data Set Comparability: Ensure that all data collected are capable of being compared
on an equal basis. This objective was met given the fact that all data sets within a test
group (i.e., the same feed material) are directly comparable since the feedstock for each
test replicate is identical and all bottles are accounted for at the end of each test.
Data Set Representativeness: Ensure that the data collected are representative of
materials typically encountered in the recycling industry. This objective was met given
the fact that the majority of the bottles was obtained directly from actual curbside
collection programs.
FEED MATERIAL
The majority of the containers used in the tests were obtained through local curbside collection
programs. The required number of post-consumer PVC and opaque HOPE bottles could not be obtained
from local curbside collection programs. Thirty unused PVC bottles and 110 unused opaque HOPE
bottles were obtained from local manufacturers to supplement the 150 post-consumer PVC bottles and
the 658 post-consumer opaque HOPE bottles needed to perform the testing. Only whole, uncrushed
bottles were selected for processing; all badly damaged containers were removed from the supply. The
opaque HOPE feedstock was selected so as to exclude large bottles that, because of their physical size,
would consistently report to the oversize station. Some bottles became deformed by the mechanical
separation equipment as a result of repeated testing; these were replaced with the same type of bottle so
as not to affect reproducibility of the recovery data for that bottle type.
The types of containers used in the testing were as follows:
Natural HDPE: Milk bottles, spring water bottles, and kitty litter containers. All were one
gallon in size, and all were virtually identical in shape.
PVC: Primarily edible oil containers, shampoo containers, and household cleaner
containers. The shape and size of these bottles varied widely.
Clear and Green PET: All soda bottles, ranging in size from 1 to 3 liters. Over half were
1 liter; less than a dozen were 3 liter. Some included basecups while others did not.
15
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Opaque HDPE: Primarily laundry detergent, orange juice, and bath lotion containers, as
well as a few dozen small size "pill" bottles.
Average bottle weights were determined for each of the five bottle types used in the testing, as
follows: natural HDPE - 64 grams, PVC - 59 grams, clear PET - 71 grams, green PET - 78 grams, and
opaque HDPE - 101 grams. The difference in clear and green PET average weights was due to the
difference in the relative quantities of 1, 2, and 3 liter bottles.
The mixed composition test feedstock was prepared to approximate the average of four mixed
plastics compositions reported in the literature by third party sources. When the representative
published data included other miscellaneous plastics, the data were normalized to include only the five
resin types used in the testing. These compositions are presented in Table 2.
TABLE 2. TYPICAL PLASTICS COMPOSITIONS,
PERCENT BY WEIGHT
Source
Bottle type
Natural HDPE
PVC
Clear PET
Green PET
Opaque HDPE
1
23.4
7.4
16.3
5.4
47.5
2
24.6
5.8
18.5
6.1
45.1
3
23.1
7.0
17.8
5.9
46.1
4
20.4
5.4
21.7
5.4
47.1
Average
22.9
6.4
18.6
5.7
46.5
Sources
Note: Numbers provided were normalized to include only the five bottle types of interest.
1 - Chemical Week, July 25,1990.
Overall HDPE number provided - assumed 33% natural HDPE, 67% opaque HDPE.
Overall PET number provided - assumed 25% green, 75% clear.
Numbers provided are weight percents of total plastics packaging.
2 - Wrapped in Plastics, The Environmental Case for Reducing Plastics Packaging,
Jean Wirka, Environmental Action Foundation, Washington DC, August 1988.
Numbers provided are 1387 sales in millions of pounds.
3 - Resource Recycling's Plastics Recycling Update, February 1991.
Numbers provided are 1990 Modern Plastics data for plastics production
in millions of pounds.
Overall PET number provided - assumed 25% green, 75% clear.
4 - Resource Recycling's Plastics Recycling Update, February 1991.
Numbers provided are Rhode Island data for the plastics composition in MSW.
16
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PRODUCT CONTAMINATION
Product contamination in the context of this report refers to the unintentional mixing of one resin
with another. Industry-wide product purity standards have not been established for the plastics products
generated by primary collectors/processors such as Material Recycling Facilities (MRFs). Each end user
or intermediate processor that purchases the materials from the primary collectors/processors
establishes the purity requirements for the materials they purchase. The basis for the specific
requirements extend beyond the chemical compatibility of resins to include facility-specific processing
capabilities and economic tradeoffs between purchase, processing, and sell costs. Thus, the
specifications for MRF-generated plastics are somewhat subjective and can vary considerably from
processor to processor.
From a chemical compatibility viewpoint, the major concern is PVC/PET contamination. PVC
and PET are virtually incompatible with one another in the reformulation of either PVC or PET pellets.
As such, they require nearly complete separation in any bottle sorting system. The specific gravity of
PVC and PET are very close, rendering the conventional gravity separation techniques used by
intermediate processors ineffective. Manual separation at a MRF is not reliable or sufficiently accurate
because of the visual similarity between some PVC and PET bottles.
The maximum allowable concentration of PVC in PET depends on the end use of the PET
product but generally is only in the range of 10 to 200 parts per million (ppm). High end use PET
products such as packaging require PVC contamination no greater than 10 ppm, while lower end uses of
PET in fiber production and some chemical recycling processes permit higher levels of PVC
contamination. The limitation on PET in PVC is similar. Since the PET and PVC cannot be easily and
reliably separated by the intermediate processor, the intermediate processor typically transfers material
quality responsibility to the MRF. To better illustrate the nature of the quality requirements, in a load of
equally sized bottles, 10 ppm is one bottle in 100,000 or 0.001 percent, and 200 ppm is one bottle in
5,000, or 0.02 percent. In practice, this stringent level of contamination is essentially zero for all practical
purposes.
Of the five bottle types used in the testing, the second major material combination limited by
chemical incompatibility in product reformulation involves opaque (copolymer) and natural
(homopolymer) HOPE. Each of these two HOPE resins can only accommodate a limited amount of
contamination by the other, above which its physical properties deteriorate.
All other combinations of resins are restricted by color incompatibility or by economics. The
economics of both the MRF's and the intermediate processor's operations are affected by the product
contamination levels. The party that performs the contamination removal receives the economic benefit
either through higher product revenues or through lower purchase costs. With proper economies of
scale, the economic benefit can exceed the cost.
The standards presented in Table 3 represent the contamination specifications in weight percent
that typically could be required by an intermediate processor purchasing baled plastics from a MRF. The
specifications are based on the material purchase specifications currently in use by five secondary
processors. Less stringent specifications may be required by some processors, while more stringent
requirements may be required by others. The specific circumstances of each case will determine the
exact limits.
The feedstock for the test program contained little if any incidental contamination. Incidental
contamination can be miscellaneous materials not associated with or related to the container types to be
recovered, and from items typically found on or related to bottles such as caps, safety seals, bottle
17
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pieces, custom colored PET bottles, PET-G bottles (containing glycol), residue from the containers'
product, and metallized labels. These contaminants can serve to reduce the allowable contamination
contribution from whole bottles.
TABLE 3. ASSUMED PRODUCT CONTAMINATION LIMITS
Product
Natural
HOPE
Contaminant, weight percent
PVC
Clear
PET
Green
PET
Opaque
HDPE
Natural HDPE
PVC
Clear PET
Green PET
Opaque HDPE
5 *
5 *
5 *
5
2 *
0
0
2 *
2 *
0 **
10
2 *
1
5 *
5 *
5 *
2 *
(a) All weight percentages marked with a single or double asterisk (* or **) are the
total weight percentages allowable for all such marked contaminants combined in
the total product. For example, in the natural HDPE product, up to 2% of either PVC,
clear PET, or green PET is allowed as a contaminant. Also, when more than one
contaminant is present, the combined contamination may not exceed 2%.
In order to compare the test results to the product specifications, the numerical count data
collected were converted to weights using the average bottle weights. Direct conversion from counts to
weights in this manner assumes that each bottle type's average weight can be reasonably applied to all
of that type's bottle counts without regard to the station at which that type of bottle was recovered. For
example, it is assumed that the average weight of the opaque HDPE bottles recovered at any particular
station is not biased away from the average weight of the entire supply of opaque HDPE bottles because
of some characteristic of the system or the feedstock, such as the bottle's shape or size.
TESTS PERFORMED
A total of 82 test runs were performed over the 2 weeks of testing. Table 4 summarizes the test
conditions and number of replicates for each test series.
Single Composition Tests
The purpose of evaluating the performance of the system in processing single composition
feedstock was to determine the recovery capability of the system without the influence of dissimilar
bottle types. Investigation of this process mode is not purely academic, as single composition feed could
effectively occur in a commercial system when large slugs of similar bottles are being fed or if the system
were to be used for a quality control check on pre-sorted bottles.
18
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TABLE 4. TESTS PERFORMED
Feed material
Conveyor C2
speed, %
Natural HOPE
PVC
Clear PET
Green PET
Opaque HOPE
1,000 mixed bottles
2,000 mixed bottles
2,000 mixed bottles *
75
25
40
50
75
90
25
50
75
90
25
75
90
50
75
50
75
90
60
Number of
replicates
3
4
4
5
3
2
4
4
2
2
7
5
3
3
1
6
1
15
Extended mixed bottle tests
The QA Plan specified that a total of 75 single composition tests would be performed (five
repetitions of three speeds for five bottle types). Longer than estimated post-test bottle counting
(subsequently shortened as discussed in Section 5) and repeated failure of the kick wheel motor reduced
the available test time. Selected tests were eliminated to meet the time constraints, resulting in a total of
50 tests being performed. The selection of which tests to eliminate was based on an evaluation of
previous test results together with a consideration of the relative magnitude of the single composition
feed rate versus the "effective bottle feed rate" expected in the mixed composition test. This concept is
defined in the Glossary of Terms and is discussed later in Section 5. Thus, the intent of each test series
was maintained. Justification for test elimination is presented below.
19
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Single composition testing of natural HOPE was limited to one speed setting because of the high
recoveries achieved at that speed, and to minimize the physical damage to the bottles from the paddle
wheel.
Testing was limited to two replicates in three test series: green PET at the 25 percent and the
90 percent speed settings, and opaque HOPE at the 25 percent speed setting. Several factors were
influential in the decision to abbreviate the green PET testing. First, green PET testing followed the
successful completion of the clear PET testing. Both PET sensors operate on the same principle, and
both types of PET are similar in size and shape (the ideal size and shape of bottles for which the system
was designed). As such, the performance of the clear PET sensor is a good indicator of the
performance of the green PET sensor. The excellent recoveries achieved for the two green PET test
replicates (97 and 98 percent) combined with the similarity with the clear PET results justified termination
of this test series. Another factor was the extremely low bottle feed rates at the 25 percent speed
setting. Completion of several replicate tests at these very low feed rates was not practical, since more
informative tests could be run at higher feed rates. This factor applied to both the green PET and the
opaque HOPE tests.
\
The calculated bottle recoveries were numerically equal for the two 90 percent green PET tests.
This, in addition to the justification provided for the 25 percent test series, resulted in the decision to
abbreviate the 90 percent green PET test series so that additional time would be available for the mixed
composition testing.
The 25 percent opaque HOPE test series was abbreviated for similar reasons as those for the
green PET testing. Recovery results from the first two replicates were well above the desired value, and
the bottle feed rate was very low at 23 bottles per minute (bpm). This test series was considered to be
low in priority and was therefore terminated at two test replicates.
PVC testing was restricted to the 25 and 40 percent speed settings because of the poor results
obtained at those levels. Processing at higher speed settings was considered to be meaningless as
recoveries were not expected to improve and most likely would decrease. Moreover, the effective bottle
feed rates (see Glossary of Terms) for individual bottle types in mixed bottle processing are expected to
be much lower than the single composition feed rates, which was confirmed during the mixed
composition testing.
Approximately 300 bottles were processed during each of the single composition short-term tests
with the exception of the PVC tests. The PVC tests consisted of only 180 bottles due to an insufficient
supply of these containers.
Mixed Composition. Short-Term Tests
The purpose of the mixed composition, short-term tests was to evaluate the bottle recoveries
resulting from the processing of a mixed feed stream, to obtain RAM data to the extent that a pilot scale
system would permit a meaningful evaluation, and to establish the operating conditions for the mixed
composition extended tests. Three series of mixed composition, short-term tests using approximately
1,000 bottles were performed at 50, 75, and 90 percent feed conveyor settings. Three replicates were
performed at each feed conveyor setting, for a total of nine tests.
The nine short-term 1,000 bottle tests were supplemented with eight mixed composition, 2,000
bottle tests. One test was performed at the 50 percent speed setting, six at 75 percent, and one at 90
percent. This resulted in a total of 17 mixed composition, 1,000 and 2,000 short-term tests being
20
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performed, compared to the 25 short-term tests specified in the QA Project Plan. Although the number
of test runs was reduced, the total number of bottles actually processed (approximately 25,000) was the
same as that originally planned.
Several voluntary system changes were implemented by the technology developer between the
conclusion of the mixed composition, short-term tests and the initiation of the extended tests. The PVC
sensor was lowered to allow detection of low profile PVC bottles. Flexible metal diverters were added to
conveyor C5 to assist in aligning the PVC bottles against the conveyor skirting. These changes were
designed to position PVC bottles closer to the sensor in an attempt to improve the PVC recovery
accuracies. The air jet pressure was increased from 100 psia to 130 psia to minimize line pressure
fluctuations when more than one station required air pressure at the same time.
One mixed composition, 2,000 bottle short-term test was performed at both the 50 percent and
90 percent speed settings strictly to provide bracketing data to assist in the selection of test conditions
for the mixed composition extended tests. These tests provided data for comparison to the mixed
composition 1,000 bottle test results to roughly assess the effect of the system changes.
Mixed Composition Extended Tests
The mixed composition, extended test series consisted of 15 segments using the 2,000 bottle
mix at a 60 percent feed conveyor speed setting. Four of the tests were found to be statistically
nonrepresentative (i.e., outliers) and were consequently eliminated from analysis. A total of 21,115
bottles were fed during the remaining 11 statistically valid test replicates. The total run time for the 11
test replicates was 4 hours, 47 minutes and 36 seconds.
Determination of Bottle Feed Rate
It was originally believed that the system performance would be inversely related to the bottle
feed rate in that recovery would decrease with increasing feed rates. However, the test results from the
single composition and short-term mixed composition tests did not show any clear, consistent
relationship between bottle recovery and bottle feed rate for the individual materials. Initially this was
surprising, but careful consideration of the test results provided insight into the mechanics of feed rate
control and its relationship to system performance.
All conveyors operate at the same speed regardless of the desired overall bottle feed rate with
the exception of conveyor C2. This is because the sensor/air jet timing and air blast duration are set for
a specific presentation conveyor (C5) speed, approximately 330 feet per minute. The overall target
bottle feed rate is set by adjusting the speed of conveyor C2. This conveyor discharges in slugs (a slug
consisting of the contents of one cleat pocket of conveyor C2). By slowing or speeding up this conveyor,
the time between slugs is either decreased or increased. A slug may consist of any number of bottles up
to the capacity of the cleat pocket, which is approximately five bottles depending on the bottle types
involved.
The slug of bottles is discharged onto conveyor C3 which feeds the three-section singulating
conveyor C4. If the cleat pocket contained oversize bottles that were removed by the oversize station
paddle wheel, no bottles would be delivered to conveyor C3 and a feed gap would occur. Feed gaps
also occurred as a result of the fallback of improperly seated bottles as they were conveyed up inclined
conveyor C2 or when knocked down by the paddle wheel. Falling bottles often knocked other bottles out
of their cleat pocket, reducing the number of bottles in that cleat.
21
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Because conveyor C4a operates at a lower speed than conveyor C3, it, rather than conveyor C2,
truly serves as the metering device for the presentation conveyor C5. If a constant supply of bottles is
provided to conveyor C4a, the bottles are drawn apart (i.e., singulated) by conveyor C4 at a uniform rate.
The increasing speeds of conveyors C4a, C4b, and C4c automatically separate the bottles provided they
are presented sequentially without any significant overlap. The resulting feed rate is the maximum feed
capacity of the system. It can be increased only by delivering bottles at a rate such that they overlap on
conveyor C4 and cannot be properly singulated, leading to recovery problems.
On the other hand, the feed rate can be decreased if bottles are delivered to conveyor C4a by
conveyor C2 at a rate below the singulating capacity of conveyor C4a. Again, it is stressed that all
bottles are presented to the sensors at a constant speed. The sensors only require milliseconds to
identify bottles and do not require any equipment recovery time between bottles. Sufficient bottle
spacing by conveyor C4 and correct bottle orientation are the two requirements for the identification
sensors and the air jets. Thus, the bottle recovery capabilities of the identification/separation equipment
should be relatively constant at feed rates that do not exceed conveyor C4's singulation capability
provided that proper bottle alignment with respect to the sensors is maintained.
Generally speaking, the bottle feed rate range utilized for the testing did not exceed the capacity
of conveyor C4 to properly singulate the bottles. This is not to say that all bottles were properly
singulated and aligned with the sensors; bottle interaction and bouncing contributed to improper
presentation. The slug feed method employed combined with the step down in conveyor speed at the
C3-C4a transition have the potential for temporarily overloading conveyor C4's capability to properly
singulate bottles. This can occur at any speed since it is a characteristic of the system.
A characteristic of the system that was affected by feed rate was feed chute and conveyor
plugging. Because of the frequency of occurrence, all plugs were manually cleared and the affected
bottles manually metered back into the flow as evenly as possible. At high speed settings, the plugs
typically involved more bottles than at low speed settings, making the manual metering of the affected
bottles more difficult. Bottles not properly reintroduced into the stream had the potential for erroneous
identification and separation. This was a consideration when selecting the speed for the extended test
series.
No one bottle feed rate resulted in all QA objectives being met. Because of this and because the
feed rate was not found to be directly related to the system performance, selection of the speed setting
for the extended tests was somewhat subjective. The feed conveyor speed setting selected for the
mixed composition, extended tests was 60 percent. This speed was considered to be a good,
representative speed that accommodated the characteristics of both the delivery system and the
identification/separation system equipment.
DATA REDUCTION, CALCULATION, AND VALIDATION METHODS
The data collected during each mixed composition, 2,000 bottle extended test run are presented
in Appendix A. The data show all raw data bottle counts recorded during these tests, test duration,
calculated feed rate, and any observations noted during the tests. Appendix B contains the calculated
results of the raw data for the mixed composition 2,000 bottle extended tests without outliers. Appendix
C contains the bottle counts and weight percentages for each component of the products generated in
the mixed composition 2,000 bottle extended tests. Data sheets similar to those shown in Appendices A,
B, and C were prepared for all test runs. Only the mixed composition, 2,000 bottle extended test data
are included, however, as these data represent the most meaningful and relevant conditions for
assessing the system's commercialization potential. Data for all test conditions including single and
short-term mixed composition tests are available from the EPA Project Officer.
22
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To demonstrate the calculations, Tables 5 and 6 present PVC data excerpted from Appendices
A and B. Table 5 presents the raw PVC data and Table 6 presents the calculated PVC results for the
extended test. Data for tests identified as outliers are not included in Table 6. Subtable B-2.1 of Table 6
contains the actual bottle recovery counts and the effective bottle feed rates. A check total is provided
for each test replicate. Also, a total is provided for each identification/separation station.
Subtable B-2.2 of Table 6 contains the bottle recoveries expressed as a percentage of the PVC
bottles fed into the system. Sample mean, standard deviation, relative standard deviation, and 95
percent confidence intervals on the mean and standard deviation are included. The data presented in
this subtable define the ability of the system to recover the intended bottles at the intended stations. For
example, from the PVC column in Table 5 (or the Test 1 column, Table 6, subtable B-2.1), the number of
PVC bottles fed into the system is 108, calculated as the total number of PVC bottles used (112) less the
unfed bottles (4), and the number of PVC bottles recovered at the PVC station is 93. Thus, the
percentage of PVC bottles recovered at the PVC station based on the number of PVC bottles fed is 100
x 93/108 = 86.1 percent recovery, as shown in subtable B-2.2 of Table 6.
TABLE 5. TEST DATA AS COLLECTED (REPLICATE 1 OF EXTENDED TEST)
(Extracted from Appendix A, Table A-1)
A-1.1 TEST 1
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
Nat HOPE
Station 1 - Natural HOPE 479
Station 2 - PVC
Station 3 - Clear PET
Station 4 - Green PET
Station 5 - Opaque HOPE
Station - Unfed 15
Station - Spillage
Total 494
Observations:
DATE: 10/07/92
PVC
1
93
10
2
1
4
1
112
Noted that bottles can jam sideways on conveyor C3
length of a 1 liter PET bottle.
Four jams were caused by PET bottles, and
Three PVC bottles were detected and blown
ended up in the clear PET station.
The fallback from the infeed conveyor was
25, and 16.
The number of oversize' chute pass-through
10 jams
COMPONENT
Clear PET Green PET
3
3
424
13
4
9
456
- the skirting
were caused by
at the PVC station but
noted as
2
7
121
8
5
1
144
width is
DURATION: 27.
FEED RATE: 71
Opaque HOPE
42
11
30
8
639
36
2
768
0 minutes
BPM
Total
525
109
471
144
652
69
4
1974
nearly identical to the
HOPE bottles.
failed to
fallback occurrences per
occurrences were noted
sen minute
enter the chute. They
minute: 13,
: 11, 12, and
18, 28,
12.
23
-------
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24
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Subtable B-2.3 of Table 6 contains bottle recoveries as a percentage of the PVC bottles actually
presented to the PVC station. As with subtable B-2.2, the sample mean, standard deviation, relative
standard deviation, and 95 percent confidence intervals are included. These data describe the ability of
the identification/separation equipment to recover bottles correctly without their being biased by the
premature bottle recovery of prior stations. Because most spillage occurred in the feed process, spillage
is assumed to occur prior to any of the identification/separation stations. For example, from the PVC
column in Table 5, the number of PVC bottles presented to the PVC station is the sum of the bottles
removed by the PVC station and all downstream stations, or 93+10+2+1 = 106. Also from Table 5, the
number of PVC bottles removed at the PVC station is 93. Thus, the percentage of PVC bottles
recovered at the PVC station based on the number of PVC bottles presented to the PVC station for test 1
is 100 x 93/106 = 87.7 percent, as shown in Table 6.
Data are presented for all stations, however, only specific combinations of bottle types and
stations have any practical meaning. Most meaningful is bottle recovery expressed as a percentage of
bottles of the same type presented to its own station. For example, PVC recovery at the PVC station
expressed as a percentage of the PVC bottles presented to the PVC station is far more meaningful than
PVC recovery at the green PET station expressed as a percentage of the PVC bottles recovered at the
green PET station. Other combinations such as clear PET recovery at the green PET station expressed
as a percentage of the clear PET bottles presented to the green PET station is also meaningful since
clear PET can be legitimately removed by the green PET station.
Subtable B-2.4 of Table 6 contains bottle recoveries expressed as a percentage of the total
bottles recovered at each station (i.e., the product), and as such is only applicable to the mixed
composition tests. The percentages at stations other than the proper station for the subject bottle type
show the contamination level in terms of bottle counts for that bottle type in that product. As with
subtable B-2.2, the sample mean, standard deviation, relative standard deviation, and 95 percent
confidence intervals are included. These values represent the product purity or grade in terms of
numbers of bottles. For example, the Station 2 line in Table 5 shows the total number of bottles
recovered at the PVC station to be 93+3+2+11 = 109. Also from Table 5, the number of PVC bottles
removed at the PVC station is 93. Thus, the percentage of PVC bottles recovered at the PVC station
based on the total number of all types of bottles recovered at the PVC station is 100 x 93/109 = 85.3
percent, as shown in subtable B-2.4 of Table 6. This represents the product purity expressed in terms of
numbers of bottles; the contamination level expressed in terms of numbers of bottles is 100 - 85.3 =
14.7 percent.
Table 7 (excerpted from Appendix C, Table C-1) demonstrates the calculation of component
weight percentages. The component weight percentages describe the product purity and contamination.
Subtable C-1.0 shows the average bottle weight for the five bottle types used in the testing and the
allowable weight percentage of each type in each product. Using these average bottle weights, the
weight percentage of each product component was calculated and compared to the allowable
contamination limit. If the weight percentage exceeded the allowable limit, it is identified with an asterisk
(*). If a product is contaminated by at least one contaminant, the product total is identified with an
asterisk preceded by the number of materials excessively contaminating the product. These calculations
are demonstrated in the following paragraph using the PVC product numbers and weight percentages
shown in Table 7.
25
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TABLE 7. BOTTLE COUNTS AND WEIGHT PERCENTAGES
(REPLICATE 1 OF EXTENDED TEST)
(Appendix C, Table C-1)
C-1.0
Bottle Type
Average Bottle Weight
Natural HOPE Product
PVC Product
Clear PET Product
Green PET Product
Opaque HOPE Product
ALLOWABLE WEIGHT PERCENT CONTAMINATION LIMITS
Hat HOPE PVC
64 grams 59 grams
100.00 2.00
5.00 100.00
5.00 0.00
5.00 0.00
5.00 2.00
Clear PET
71 grams
2.00
0.00
100.00
10.00
2.00
Green PET
78 grams
2.00
0.00
1.00
100.00
2.00
Opaque HOPE
101 grams
1.00
5.00
5.00
5.00
100.00
Maximum confined opaque and natural HOPE contamination in either clear PET, green PET, or PVC is 5%.
Maximum combined PVC, clear PET, and green PET contamination in either natural or opaque HOPE is 2%.
Maximum combined PET contamination in PVC is 0%.
C-1.1 TEST 1
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
DATE:
DURATION:
FEED RATE:
10/07/92
27.0 minutes
71 BPH
COMPONENT
Natural HOPE Product
PVC Product
Clear PET Product
Green PET Product
Opaque HOPE Product
Nat HOPE PVC
No./Wt % No./Wt %
479/87.17% M 0.17%
93/78.76%
10/ 1.72%*
2/ 1.05%*
1/ 0.09%
Clear PET
No./Wt %
3/ 0.61%
3/ 3.06%*
424/87.84%
13/ 8.18%
4/ 0.43%
Green PET
No./Wt %
2/ 2.24%*
7/ 1.59%*
121/83.62%
8/ 0.95%
Opaque HDPE
No./Wt %
42/12.06%*
11/15.95%*
30/ 8.84%*
8/ 7.16%*
639/98.52%
Total
No./Ut %
525/100% 1*
109/100% 3*
471 /100% 3*
144/100% 2*
652/100%
The PVC product consisted of four components: PVC, clear PET, green PET, and opaque
HDPE. The total weight of the PVC component is calculated as the product of the number of PVC
bottles and the average weight of a PVC bottle, or 93 x 59 = 5,487 grams. Likewise, the weight of the
clear PET component is 3 x 71 = 213 grams, the weight of the green PET component is 2 x 78 = 156
grams, and the weight of the opaque HDPE component is 11 x 101 =1,111 grams. The total weight of
the PVC product is 5,487 + 213 + 156 + 1,111 = 6,967 grams. The weight percentage of the PVC
component is therefore 100 x 5,487/6,967 = 78.76 percent, and the weight percentage of the clear PET
component is 100 x 213/6,967 = 3.06 percent. Similar calculations for green PET and opaque HDPE
yield 2.24 and 15.95 percent, respectively. The clear PET, green PET, and opaque HDPE weight
percentages exceed the allowable contamination limits shown in the table, hence they are identified with
an asterisk.
TEST PROCEDURES AND QA CHECKS
Procedures Common to All Tests
Prior to each test, a sample of bottles were run through the system to verify the operation of the
identification/separation equipment. For the single composition tests, five bottles of the appropriate type
were run, and for the mixed composition tests, two of each bottle type were run. This quick check
ensured that all sensors and air jets were operational.
After loading the feed bin with the appropriate feedstock, the system was "primed" by running
conveyor C2, along with the paddle and kick wheels, to fill up the cleats with bottles. As the first filled
cleat approached the paddle wheel, C2 was halted. In this way, each test began with an "instantaneous"
26
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flow. Each test was terminated when there was an insufficient amount of containers in the feed bin to fill
the cleats of conveyor C2. Conveyor C2 was stopped at the test end, and all other conveyors were
allowed to run out so that bottles fed during the test period could be separated by the system and
included in the test results. This procedure ensured that feeding was initiated exactly at the start of the
test and that there was no appreciable feed rate drop-off at the end of the test due to an insufficient
supply of bottles in the feed bin. All test times were recorded using 24 hour time, and all clocks used for
timing were synchronized at the start of each day.
The only available method of controlling the bottle feed rate, by virtue of the system design, is by
varying the speed of conveyor C2. The speed setting is adjustable from 0 to 100 percent. Actual bottle
feed rates vary by type of feed for the same speed setting percentage, since the number of bottles per
cleat is a function of the bottle size and shape, and bottle sizes vary by type. Speed setting selections
were based on advice from the CPRR operators. AH test speeds were recorded in terms of the percent
of the maximum speed of conveyor C2, and resulting bottle feed rates were calculated.
Procedures Specific to Single Composition Tests
Prior to conducting the single composition tests, the bottles were counted and stored in marked
gaylord containers. Initially, every bottle was counted at the conclusion of each test. Subsequently, the
counting procedure was changed such that only the bottles spilled, unfed, or those that reported to an
incorrect station were counted. The sum of these counts was subtracted from the total number of bottles
to arrive at the quantity reporting to the proper station. This procedure dramatically accelerated the
counting procedure since the majority of the bottles reported to their proper station. At the conclusion of
the testing for each material type, all bottles of that type were again counted to ensure that all were
present and accounted for.
Spot feed rate checks were performed at various times throughout the single composition tests
to note the variability in bottle feed rate. A continuous, quantitative analysis of bottle feed rates was
performed on a representative extended test, discussed later.
Procedures Specific to Mixed Composition Tests
The same feedstock used for the single composition test was used to prepare the mixed
composition feedstock. Bottles were added as necessary to meet the required total count. As indicated
earlier, the mixed composition feedstock followed the proportions specified in Table 3. Following each
test run, re-mixing of the feed for the subsequent test was required. Re-mixing was accomplished
through the sequential layering of the five types of bottles into gaylord boxes according to their
percentage in the mixture. Small gaylords were used to facilitate filling and feed bin loading;
approximately 125 mixed bottles could be placed in a box. Eight boxes were required for the 1,000
bottle tests, and 16 were required for the 2,000 bottle tests. Each box was filled with two layers of each
bottle type. For example, the sequence for remixing one box for the 1,000 bottle test feed was: 1/16 of
the total natural HOPE, 1/16 of the total PVC, 1/16 of the total clear PET, 1/16 of the total green PET,
and 1/16 of the total opaque HOPE; all steps were repeated twice. Although the polymer type sequence
may have varied across test re-mixes, one layer of each type was placed before the second layering
sequence was begun. This procedure helped to achieve a somewhat controlled mixture of bottles
across the mixed composition tests.
At the conclusion of each test, the spilled containers and the unfed containers were collected
and boxed. The products from each station were sorted to remove all foreign bottles. These improperly
separated bottles or "mistakes" and the spilled and unfed bottles were counted by type by two
independent counters. The total mistakes for each type were subtracted from the total number of each
type fed to arrive at the number of bottles correctly reporting to the proper stations. At the conclusion of
27
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the mixed testing, the total bottle count was rechecked to ensure that no bottles were lost during the
testing. This procedure eliminated the time-consuming and tedious chore of counting every bottle after
each test run without compromising quality assurance. The fact that the initial and final bottle counts
agreed for the two short-term and the one extended mixed composition test series attests to the
effectiveness of this procedure.
Data Validation
Selected results from each test series were subjected to the Modified Three-Sigma Test for the
determination of outliers. This method is a modification of the standard Three-Sigma Test, and accounts
for the fact that the probability of outliers increases as the sample size (defined as the number of test
replicates performed) increases^. Observations rejected on the basis of the Modified Three-Sigma
Test have a 99 percent chance of being an outlier.
Since the number of bottles fed out of the feed bin varied from test to test, the actual bottle
recovery counts could not be used in the determination of outliers. To normalize the data, each bottle
recovery count was first expressed as the percentage of bottles of the same type fed into the system
(percent of bottles fed) and then as the percentage of the product in which it appeared (percent of total
recovered). The resulting values were used in two separate outlier calculations. A third outlier
calculation was performed using the overall bottle feed rate for each test. Any test identified as an outlier
by any of the three calculations was rejected.
The 95 percent confidence intervals were established for sample means using the "Student's" t
distribution. Because these values are percentages, all negative confidence intervals were reported as
zero, and all confidence intervals exceeding 100 were reported as 100. Similar confidence intervals
were established for sample standard deviations using the Chi-Square Distribution.
28
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SECTION 5
TEST RESULTS
The single composition, mixed composition short term, and mixed composition extended tests
were performed for different and distinct reasons. Each test type provided valuable data and knowledge
that benefited subsequent tests. Single composition tests, performed first, were the simplest test type
and thus provided baseline level data on the performance of each identification/separation station. The
next test type, the mixed composition short term tests, provided data needed to establish the test
conditions for the mixed composition extended tests. Finally, the mixed composition extended tests
provided system performance data at specific conditions for an extended period. The results obtained
for each test type are discussed separately in this section in the order in which they were performed.
SINGLE COMPOSITION TESTS
Single Composition Bottle Recovery. Percent of Bottles Fed
Table 8 presents the mean and average lower 95 percent confidence limit for the bottle
recoveries as well as the average feed rates for the single composition test series. All recoveries are
based on the number of bottles fed.
As shown in Table 8, natural HOPE easily exceeded the 90 percent QA recovery objective with
95 percent confidence at a feed rate of 101 bpm. PVC failed to achieve the QA goal of 100 percent
recovery at any feed rate, and at best achieved a 95 percent confident recovery of only 77 percent at 51
bpm. It was subsequently discovered that the PVC sensor was set too high to detect the range of PVC
bottle sizes used in the testing. Following the single composition tests, the PVC sensor was lowered and
bottle recoveries improved in subsequent tests. Clear PET recovery exceeded the 90 percent objective
with 95 percent confidence at feed rates up to 126 bpm. Green PET recoveries exceeded the 90 percent
objective with 95 percent confidence at feed rates up to 120 bpm with the exception of the 24 bpm test
series (see discussion below).
Opaque HOPE recoveries failed to achieve 90 percent with 95 percent confidence at any feed
rate, although mean recoveries exceeded the desired criteria at feed rates up to 101 bpm. Because the
opaque HOPE station is a passive recovery station, poor recovery is the direct result of the prior removal
of opaque HOPE bottles by upstream stations. Opaque HOPE bottles generally did not have a round
cross-section, the shape for which the system was designed. This fact may have contributed to the low
bottle recovery.
The lower 95 percent confidence limit of green PET and opaque HOPE recovery at the 25
percent speed setting were lower than that at higher bottle feed rates because only two replicates were
performed at the 25 percent level. The lower 95 percent confidence limit of green PET at the 90 percent
speed setting escaped a similar fate despite the fact that only two replicates were performed because
both results were numerically equal.
29
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TABLE 8. BOTTLE RECOVERIES BASED ON BOTTLES FED INTO THE SYSTEM,
SINGLE COMPOSITION TESTS
Bottle type
Conveyor C2 speed setting, percent of full speed
25 40 50 75 90
Natural HOPE
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
PVC
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
79.0
77.0
51.0
74.6
67.7
80.0
99.6
98.9
101.0
Clear PET
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
Green PET
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
Opaque HOPE
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
98.0
85.4
24.0
94.8
82.2
23.0
96.6
94.0
72.0
97.9
95.1
65.0
97.5
95.1
109.0
97.4
94.3
97.0
91.4
88.7
80.0
97.4
95.7
126.0
93.8
93.8
120.0
90.7
87.3
101.0
As can be seen in Table 8, clear PET, green PET, and opaque HOPE recoveries were relatively
unaffected by changes in the bottle feed rate. PVC recovery dropped off considerably as the feed rate
increased from 51 to 80 bottles per minute.
It was observed during the first natural HOPE test replicate that to efficiently feed only natural
HOPE bottles, it was necessary to manually assist the bottles onto the infeed conveyor. The large size
and low weight of these bottles made pick up by conveyor C2's cleats difficult at high process rates
without manual intervention. This was done in subsequent natural HOPE tests. Also, the oversize chute
was not designed to handle a continuous feed of natural HOPE bottles at high throughput rates in a
single composition test. Considerable manual prodding was required to keep the chute unplugged.
30
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During testing, it was noted that heavily scratched and abraded green PET bottles were often not
detected due to an apparent scattering of the light beam by the roughened surface. Also, it was noted
that some bottles were dented from repeated impacts with the paddle wheel, affecting their presentation
to the sensors. These bottles were replaced with undamaged bottles when discovered.
Single Composition Bottle Recovery. Percent of Bottles Presented
Table 9 presents the bottle recovery results based on the number of bottles of the same type
presented to each station. These data define the performance of each recovery station as if it were
completely isolated from all other stations. The results are not affected by bottles prematurely removed
as contaminants prior to their proper station. Table 9 presents only data for each material at its own
station. Perhaps the most meaningful bottle type/station combination is the data describing the capability
of the green PET station to recover clear PET. Recoveries at the opaque HOPE station are naturally 100
percent, since all bottles presented to this station cannot report elsewhere, by virtue of its passive
recovery method and its position at the end of the processing system.
TABLE 9. BOTTLE RECOVERIES BASED ON BOTTLES PRESENTED TO EACH STATION,
SINGLE COMPOSITION TESTS
Bottle type
Conveyor C2 speed setting, percent of full speed
25 40 50 75 90
Natural HOPE
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
99.6
99.1
101.0
PVG
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
79.1
77.2
51.0
74.8
68.2
80.0
Clear PET
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
96.8
90.7
72.0
97.8
95.1
109.0
98.2
96.1
126.0
Green PET
- Mean recovery, % 99.2
- Lower 95% confidence limit, % 91.2
- Feed rate, bottles per minute 24.0
Opaque HOPE
- Mean recovery, % 100.0
- Lower 95% confidence limit, % 100.0
- Feed rate, bottles per minute 23.0
99.2
98.4
65.0
98.8
97.8
97.0
100.0
100.0
80.0.
96.5
94.7
120.0
100.0
100.0
101.0
31
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Bottle recoveries at the natural HOPE, PVC, and clear PET stations based on the number of
bottles presented to these stations did not increase over those based on bottles fed due to the low
number of bottles spilled and removed by prior stations. Bottle recoveries based on the number of green
PET bottles presented to the green PET station were considerably higher than those based on green
PET bottles fed into the system due to the loss of green PET to spillage and to the clear PET station.
The 95 percent confidence green PET recovery at the 25 percent level met the 90 percent QA objective
when based on bottles presented while it did not meet the objectives based on bottles fed.
Any clear PET bottles not recovered at the clear PET station were candidates for removal by the
green PET station because of the similarity in the optical techniques used to identify the PET bottles.
The average removal efficiency of the green PET station with respect to clear PET bottles presented to it
ranged from 94.2 to 73.3 percent. Surprisingly, these recovery rates decreased significantly with
increasing feed rate, whereas similar values for the clear PET station actually increased slightly. The
difference in recovery cannot be definitively explained.
Single Composition Test Bottle Feed Rates
As shown in Table 8, the single composition test data show that there is no correlation between
the infeed conveyor speed setting and the bottle feed rate for bottle types that vary considerably in size
and shape from one another. For example, a 25 percent feed setting for PVC resulted in an average
feed rate of 51 bpm, whereas the same setting resulted in an average feed rate of 23 bpm for opaque
HOPE. Many opaque HOPE bottles were much larger than most PVC bottles, consequently fewer can
be contained in a cleat pocket on the infeed conveyor. Further, infeed conveyor fallback was much more
pronounced with opaque HOPE bottles due to their large size.
Spot rate feed rate checks were performed randomly during the testing. The check consisted of counting
the bottles passing a selected point for a certain period of time. The selected point was located on
conveyor C6 for natural HOPE and on conveyor C3 for all other bottle types. The feed rates determined
from conveyor C3 naturally varied considerably due to the periodic removal of natural HOPE bottles prior
to conveyor C3 and bottle fallback on conveyor C2. Short term feed rates were found to vary
considerably.
MIXED COMPOSITION, SHORT-TERM TESTS
Bottle Recovery. Percent of Bottles Fed
Table 10 presents the mean and average lower 95 percent confidence limit for bottle recoveries
based on bottles fed, and the overall and effective bottle feed rates for the mixed composition, short-term
tests. As defined in the Glossary of Terms, the effective bottle feed rate is the average rate at which a
specific type of bottle was fed during a mixed composition test, whereas the overall bottle feed rate is the
average rate at which all bottles taken as a group were fed during a test.
As discussed in Section 4, the 50 percent and 90 percent 2,000 bottle, mixed composition,
short-term tests were performed for bracketing purposes only. They are presented in Table 10, but are
not considered in the discussion that follows. As shown in Table 10, natural HOPE and both types of
PET achieved the QA objective for recovery of 90 percent with 95 percent confidence at least at one of
the feed rates investigated. The maximum conveyor C2 speed setting and corresponding overall feed
rates allowing a minimum of 90 percent recovery of HOPE and PET with 95 percent confidence are as
follows: natural HOPE - 75 percent at 98 bpm; clear PET - 50 percent at 59 bpm; and green PET - 50
percent at 59 bpm. Opaque HOPE failed to achieve 90 percent recovery with 95 percent confidence and
PVC failed to achieve its QA objective for recovery of 100 percent at any of the feed rates investigated.
32
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TABLE 10. BOTTLE RECOVERIES BASED ON BOTTLES FED INTO THE SYSTEM,
MIXED COMPOSITION, SHORT-TERM TESTS
1 ,000 Bottles
Conveyor C2 speed setting, % of full speed
Overall feed rate, bottles per minute
50
59
75
90
90
111
2,000 Bottles
50
57
75
98
90
125
Natural HOPE
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
98.6 97.8
97.9 95.3
14.0 22.0
93.5
66.0
27.0
99.8
99.8
14.0
95.9 95.8
92.7 95.8
24.0 31.0
PVC
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
77.3 79.6
71.2 41.3
3.0 5.0
79.2
72.9
6.0
92.9
92.9
3.0
82.6 90.2
76.2 90.2
6.0 7.0
Clear PET
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
93.9 90.6
90.6 84.1
14.0 21.0
88.3
84.2
26.0
92.6
92.6
13.0
88.5 92.4
82.9 92.4
23.0 29.0
Green PET
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
93.8 94.2
91.3 83.0
4.0 7.0
85.9
59.6
8.0
88.7
88.7
4.0
77.9 69.2
70.7 69.2
7.0 9.0
Opaque HOPE
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
90.9 88.8
88.8 80.7
23.0 36.0
86.1
77.9
44.0
91.1
91.1
22.0
88.0 81.7
84.7 81.7
38.0 49.0
As previously stated, the opaque HOPE recovery station is a passive recovery station; that is,
the bottles recovered are those remaining in the system after passing by other recovery stations. Thus
the performance of the opaque HOPE station is determined by the performance of the prior stations.
Bottle Recovery. Percent of Bottles Presented
Table 11 presents the bottle recovery results based on the number of bottles of the same type
presented to each station. Data are presented only for each material at its own station. Recoveries
based on bottles presented naturally improved, albeit slightly, over those based on bottles fed.
Excluding opaque HOPE, only one test series (green PET at the 75 percent speed setting) saw its lower
average 95 percent confidence limit elevated from below 90 percent (Table 9) to above the 90 percent
level (Table 11).
33
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TABLE 11. BOTTLE RECOVERIES BASED ON BOTTLES PRESENTED TO EACH STATION,
MIXED COMPOSITION, SHORT-TERM TESTS
1 ,000 Bottles
Conveyor C2 speed setting, % of full speed
Overall feed rate, bottles per minute
Natural HOPE
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
PVC
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
Clear PET
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
Green PET
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
Opaque HOPE
- Mean recovery, %
- Lower 95% confidence limit, %
- Feed rate, bottles per minute
- Feed rate, bottles per minute
50
59
98.6
97.9
14.0
77.8
72.8
3.0
94.6
91.9
14.0
97.0
92.6
4.0
100.0
100.0
23.0
75
90
98.0
95.1
22.0
82.0
44.5
5.0
93.7
87.0
21.0
99.0
95.5
7.0
100.0
100.0
36.0
90
111
93.6
66.6
27.0
80.1
71.3
6.0
91.6
86.3
26.0
92.8
80.6
8.0
100.0
100.0
44.0
2,000 Bottles
50
57
99.8
99.8
14.0
95.4
95.4
3.0
94.5
94.5
13.0
92.6
92.6
4.0
100.0
100.0
22.0
75
98
96.2
93.3
24.0
83.3
76.8
6.0
91.5
86.1
23.0
85.5
78.4
7.0
100.0
100.0
38.0
90
125
96.4
96.4
31.0
90.2
90.2
7.0
97.2
97.2
29.0
83.9
83.9
9.0
100.0
100.0
49.0
Recovery accuracies based on the number of opaque HOPE bottles actually presented to the
opaque HOPE station were naturally 100 percent since this station is the last station on the process line.
Table 12 compares selected bottle feed rates and recoveries for the single and mixed
composition tests. The values compared are effective bottle feed rates corresponding to the maximum
bottle recoveries achieved based on bottles presented. In determining the maximum recovery values,
only the lower limit of the average 95 percent confidence interval was considered. For the single
composition tests, the effective bottle feed rate is the overall bottle feed rate. This table shows that bottle
recoveries in the single composition tests were comparable to or better than those in the mixed
composition tests despite significantly higher effective bottle feed rates. This comparison serves to
illustrate the effect of bottle to bottle interference on recovery and bottle throughput rate when processing
mixed bottles typical of post-consumer recycling streams.
34
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TABLE 12. COMPARISON OF SINGLE AND MIXED COMPOSITION
SHORT-TERM TEST EFFECTIVE FEED RATES FOR MAXIMUM RECOVERIES
BASED ON BOTTLES PRESENTED TO EACH STATION
Bottle type
Natural HOPE
PVC
Clear PET
Green PET
Opaque HOPE
Single composition Mixed composition
Maximum Effective Maximum Effective
recovery, feed rate, recovery, feed rate,
percent bpm percent bpm
99.1 101 97.9 14
77.2 51 76.8 6
96.1 126 91.9 14
98.4 65 95.5 7
100.0 101 100.0 44
Product Composition
Table 13 presents the averages of the five product compositions in weight percent for each of
the replicates comprising a mixed composition, short-term test series. Also included are the allowable
limits for the product components. The primary bottle type's percentage of the total weight represents
the product's purity, and the percentages of other bottle types represent the contamination. The 50 and
90 percent 2,000 bottle test series consisted of only one replicate each. The data are presented but are
not considered in the analysis.
As can be seen from Table 13, nearly all products were excessively contaminated by at least
one material. Although the results varied somewhat with infeed conveyor speed, generally the natural
HOPE product was contaminated by opaque -HOPE, the PVC product by PET and HOPE, the clear PET
product by PVC (and green PET and HOPE in two of the four test series), and the green PET product by
PVC, clear PET, and HOPE. The opaque HOPE product was contaminated by heavy resins in two of the
four test series. Product purities also varied with infeed conveyor speed. The opaque HOPE product
had the highest purity (95 to 98 percent), followed by clear PET (86 to 94 percent), natural HOPE (85 to
90 percent), PVC (72 to 89 percent), and green PET (62 to 76 percent). There is no readily apparent
reason for the low green PET product purity.
Equipment Failure/Downtime
One equipment failure was experienced during the mixed composition, short-term 1,000 bottle
tests. Conveyor C4 developed a belt tracking problem, resulting in an 88 minute downtime during test 1
of the 75 percent speed series.
35
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TABLE 13. AVERAGE PRODUCT COMPONENTS,
MIXED COMPOSITION, SHORT-TERM TEST (IN WEIGHT PERCENT)
1,000 Bottles
Conveyor C2 Speed Setting
50%
75% 90%
2,000 Bottles *
50%
75%
90%
Limit
Natural HOPE Product
Natural HOPE
PVC
Clear PET
Green PET
Total Heavies
Opaque HOPE
89.00
0.00
0.14
0.16
0.30
10.71
84.53
0.46
1.10
0.15
1.71
13.76
88.21
0.00
0.98
0.39
1.37
10.42
86.45
0.17
0.60
0.22
0.99
12.56
90.45
0.06
0.84
0.20
1.10
8.45
88.40
0.00
0.43
0.23
0.66
10.94
100
2
1
PVC Product
PVC
Clear PET
Green PET
Total PET
Natural HOPE
Opaque HOPE
Total HOPE
Clear PET
PVC
Green PET
Natural HOPE
Opaque HOPE
Total HOPE
89.47
2.56
0.91
3.47
0.00
7.06
7.06
93.16
2.33
0.33
0.00
4.19
4.19
84.49
9.28
1.56
10.84
0.84
3.82
4.66
94.17
1.83
0.86
0.00
3.13
3.13
78.29
9.19
0.78
9.97
0.64
11.10
11.74
Clear PET
91.27
1.52
1.67
0.13
5.41
5.54
83.44
4.83
2.12
6.95
0.00
9.61
9.61
Product
95.02
0.57
0.50
0.00
3.91
3.91
71.61
9.23
3.22
12.45
1.43
14.51
15.94
85.59
1.85
1.84
0.34
10.39
10.73
57.71
11.00
3.02
14.02
1.86
26.41
28.27
80.42
1.79
4.08
0.35
13.36
13.71
100
0
5
100
0
1
5
* 50% and 90% test series consisted of only one replicate each and were used strictly for
bracketing purposes.
36
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TABLE 13. CONTINUED
Conveyor C2 Speed Setting
1,000 Bottles
0.50 0.75 0.90
2,000 Bottles *
0.50
0.75
0.90
Limit
Green PET
PVC
Clear PET
Natural HOPE
Opaque HOPE
Total HOPE
Opaque HOPE
PVC
Clear PET
Green PET
Total Heavies
Natural HOPE
Green PET Product
76.23 70.44 61.99 83.30 69.72 75.91 100
3.81 2.19 3.64
0.00
9.52
98.31
0.61
0.50 2.88 0.00
10.45 9.96 12.72 12.74 14.59
0.28
17.13
0.27
21.37
0.00
3.45
0.59
12.22
9.52 17.41 21.64
3.45 12.81
Opaque HOPE Product
97.94 95.22 98.41 95.52
0.23
0.40
0.45
1.08
0.40
0.62
0.30
1.32
0.39
0.94
1.02
2.35
0.74
2.43
0.09
0.00
1.26
22.83
24.09
95.46
0.08
0.30
1.11
1.49
0.18
1.03
2.06
3.27
0.00
1.30
2.26
3.56
1.22
0.98
0
10
100
2
5
* 50% and 90% test series consisted of only one replicate each and were used strictly for
bracketing purposes.
Two equipment failures were experienced during the mixed composition, short-term 2,000 bottle
tests. Two of the eight rubber flaps on the paddle wheel failed, resulting in downtimes of 33 and 51
minutes for repair. These failures occurred during tests 2 and 3, respectively, of the 75 percent series.
The paddle wheel rubber flap connection was noted to be deficient following these two failures, and
subsequent failure of the remaining six unmodified flaps was expected. Repeated flexing of the rubber
flap caused the rubber to shear at the connection to the paddle wheel drum. The connection detail did
not provide sufficient bearing area to prevent flexure-induced failure. This type of failure would not be
expected when using a commercial-grade mechanical paddle wheel. Repair of these flaps was
performed when necessary during the counting time between tests.
37
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MIXED COMPOSITION, EXTENDED 2,000 BOTTLE TESTS
Mixed Composition. Extended Test Results
Bottle Recovery, Percent of Bottles Fed ~
Table 14 presents the mean and average lower 95 percent confidence limit for bottle recoveries
based on bottles fed, and the effective bottle feed rates for the mixed composition extended tests. The
average overall bottle feed rate for the extended test was 74 bpm. Using the average bottle weights, the
overall throughput rate was 782 pounds per hour.
As shown in Table 14, only the natural HOPE and clear PET bottle recoveries met their QA
objectives of 90 percent with 95 percent confidence despite the low effective bottle feed rates. PVC
recovery, at 87.3 percent, was considerably below its QA objective of 100 percent. At 87.8 percent,
opaque HOPE recovery was close to the 90 percent QA objective. Overall, the system correctly
recovered 90.9 percent of the bottles fed with 95 percent confidence.
TABLE 14. BOTTLE RECOVERIES AND EFFECTIVE FEED RATES
BASED ON BOTTLES FED INTO SYSTEM, EXTENDED TESTS
Bottle type
Natural HOPE
PVC
Clear PET
Green PET
Opaque HOPE
All bottles
Average
recovery,
percent
99.1
89.3
92.8
86.5
89.4
92.4
LACI* of
recovery,
percent
98.7
87.3
90.7
83.8
87.8
90.9
Effective
feed rate,
bpm
18
4
17
5
29
74
* lower average 95 percent confidence limit
Bottle Recovery, Percent of Bottles Presented -
Table 15 presents the mean and average lower 95 percent confidence limit for bottle recoveries
based on bottles presented to each station, and the effective bottle feed rates for the mixed composition,
extenaed tests. Table 15 lists only the recovery of bottle types at their own stations; Appendix B
contains bottle recovery data for every combination of recovery station and bottle type.
38
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TABLE 15. BOTTLE RECOVERIES AND EFFECTIVE FEED RATES
BASED ON BOTTLES PRESENTED TO EACH STATION, EXTENDED TESTS
Bottle type
Natural HOPE
PVC
Clear PET
Green PET
Opaque HOPE
Average
recovery,
percent
99.1
90.2
95.1
91.1
100.0
LAC I* of
recovery,
percent
98.6
87.9
93.3
89.6'
100.0
Effective
feed rate,
bpm
18
4
17
5
29
* lower average 95 percent confidence limit
Being the last recovery station, the opaque HOPE station recovered all of the opaque HOPE
bottles presented to it. Other than opaque HOPE, the only other bottle type to see a substantial increase
in recovery over that based on bottles fed was green PET (83.6 percent based on bottles fed and 89.6
percent based on bottles presented). The value based on the number of green PET bottles presented to
the green PET station was, at 89.6 percent, very close to the QA objective of 90 percent. This indicates
that the green PET identification/separation equipment by itself was effective in recovering green PET,
but the system as a whole was not.
The green PET recovery station recovered on average 81.4 percent of the clear PET presented
to it (see Appendix B, Table B-3.3). From Table 15, this same station recovered on average 91.1
percent of the green PET presented to it. Thus, the green PET station is much less effective in
recovering clear PET as it is in recovering its primary product. This is surprising, since the optical
difference between clear and green PET should make clear PET easier to identify. Much of this
difference may be due to misalignment of the clear PET bottles presented to the green PET station. The
fact that nearly 20 percent of the clear PET bottles presented to the green PET station were missed by
both the clear and the green PET stations implies that the sensors alone are not to blame for the missed
recovery.
Product Composition --
Table 16 presents the weight percentages of each component in the five products. The
contamination limits set forth in Table 3 are also included. Only the opaque HOPE product met
contamination criteria. All other products were contaminated by at least one other resin type. Natural
HOPE had excessive opaque HOPE contamination, PVC had excessive PET and HOPE contamination,
and both clear and green PET had excessive PVC and HOPE contamination. The product purities
followed the same pattern found in the mixed composition, short-term tests. Opaque HOPE was highest
at 98 percent, followed by clear PET at 92 percent, natural HOPE 88 percent, PVC at 83 percent, and
green PET at 77 percent.
39
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TABLE 16. AVERAGE PRODUCT COMPOSITIONS,
EXTENDED TESTS
Component
Natural
Natural HOPE
PVC
Clear PET
Green PET
Total Heavies
Opaque HOPE
Weight
Percent Limit
HOPE Product
87.83 100
0.15
0.58
0.24
0.97 2
10.71 1
PVC Product
PVC
Clear PET
Green PET
Total PET
Natural HOPE
Opaque HOPE
Total HOPE
Clear
Clear PET
PVC
Green PET
Natural HOPE
Opaque HOPE
Total HOPE
83.07 100
6.53
1.94
8.47 0
0.34
8.11
8.45 5
PET Product
91.78 100
1.12 0
0.89 1
0.02
6.19
6.21 5
Component
Green
Green PET
PVC
Clear PET
Natural HOPE
Opaque HOPE
Total HOPE
Opaque
Opaque HOPE
PVC
Clear PET
Green PET
Total Heavies
Natural HOPE
Weight
Percent
PET Product
76.91
1.94
9.61
0.19
11.35
11.54
HOPE Product
97.89
0.05
0.40
1.34
1.79
0.32
Limit
100
0
10
5
100
2
5
40
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Recovery Mistakes -
The extended test data resulted in a total of 7.6 mistakes for every 100 mixed bottles fed. The
mistake distribution did not conform to the proportions of the bottle mixture actually fed, as shown in
Table 17.
As can be seen in Table 17, green PET had the largest mistakes/feed mix ratio, followed by
PVC, opaque HOPE, clear PET, and natural HOPE. With ratios larger than 1.0, green PET, PVC, and
opaque HOPE contributed more than would be expected based on the percentages of the bottles
actually fed. Natural HOPE'S low ratio of 0.1 indicates that it contributed much less than expected
toward the overall mistakes than its percentage in the overall mix might suggest.
TABLE 17. COMPARISON OF MISTAKE DISTRIBUTION TO FEED MIX PROPORTIONS,
EXTENDED TESTS
Bottle type
Natural HOPE
PVC
Clear PET
Green PET
Opaque HOPE
Total
Percent of
total fed
24.7
5.8
23.3
7.3
38.9
100.0
Percent of Ratio of
mistakes mistakes/mix
3.0
8.1
21.9
12.9
54.1
100.0
0.1
1.4
0.9
1.8
1.4
1.0
Another way of viewing the data is to compare the number of bottles of each type processed for
every one mistake. These data as tabulated in Table 18, show a wide range of error frequency. In the
worst case, one green PET bottle reports to the opaque HOPE product for every 12 green PET bottles
fed. In the best case, one natural HOPE bottle reports to the clear PET product for every 5,228 natural
HOPE bottles fed.
Unfed Bottles -
The method used to terminate a test resulted in unfed bottles remaining in the feed bin and on
the infeed conveyor. The composition of unfed bottles varied somewhat from the original mix
composition. Table 19 compares the mix composition to the unfed bottle composition.
The major difference between the original mix and the unfed compositions involves natural
HOPE and PVC containers. PVC bottles, being typically small and less prone to fallback on conveyor
C2, were more efficiently fed than the relatively large natural HOPE bottles. Also, the relative bulk
densities and bottle sizes may have affected the movement of bottles within the feed bin, and thus
41
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influenced the unfed bottle mix composition. Natural HOPE bottles, being large and thin walled, have the
lowest bulk density of the five bottle types comprising the mix. These bottles were more prone to
fallback from conveyor C2 than other types of bottles.
TABLE 18. ERROR FREQUENCY, EXTENDED TESTS
Recovery error frequency - number of bottles fed per one
Bottle Type
Natural HOPE
PVC
Clear PET
Green PET
Opaque HOPE
Natural Clear
HOPE PVC PET
station station station
1307 5228
122 - 18
159 67
128 81 38
19 130 37
Green Opaque
PET HOPE
station station
1307 138
28 203
26 115
12
53
mistake
Spillage
2614
608
290
257
746
TABLE 19. UNFED BOTTLES, EXTENDED TESTS
Mix
composition,
Bottle Type numerical %
Natural HOPE 25.0
PVC 5.7
Clear PET 23.1
Green PET 7.3
Opaque HOPE 38.9
Total 100.0
Unfed
composition,
numerical %
37.9
1.3
17.8
6.0
37.0
100.0
42
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Equipment Failure/Downtime
A total of 91 jams were noted during the 11 valid test runs comprising the extended test. These
jams were cleared immediately and did not result in any process down time.
The only equipment failures that were experienced during this test series were associated with
the oversize product paddle wheel. The rubber flaps on the paddle wheel failed five times; each flap was
replaced after it failed. The test was suspended for two of the five repairs, while the other three repairs
were made during the bottle counting and mixing period between tests. The flap replacement time was
approximately 60 minutes.
Bottle Delivery and Clear PET Station Recovery Analysis
Different views of the process line were recorded on videotape during several extended test runs
to document various aspects of the system. The clear PET and PVC stations were taped on test run 7.
The video was used to document the bottle delivery sequence and timing of all bottles not removed at
the natural HOPE (oversize) station, as well as the types of identification and recovery mistakes that
occurred at the clear PET station.
Delivery Sequence and Timing-
The videotape was viewed at 1/6 of normal speed, resulting in virtually no time lag in recording
the delivery time of each bottle on conveyor C5. The range of view in the video included the PVC station
air jets and the entire clear PET station. The enclosure around the PVC station precluded a view of the
approach to that station. Bottles removed at the PVC station could only be viewed as they were ejected
by the air jets. Thus, the delivery time recorded for bottles removed at the PVC station was the actual
time of removal.
Using the delivery time difference noted between bottles, the distance between each bottle was
calculated using a conveyor speed of 330 feet per minute, and assuming an average bottle length of 12
inches. Also calculated were the distances between bottles of similar types.
Table 20 lists the actual counts of bottles fed onto conveyor C5 and the counts determined from
the video. The accuracy of the visual rendering of the video is considered high, with only five bottles out
of 1,377 missed, or 0.36 percent. Even when viewed at slow speed, the high speed of the bottles as
they were ejected coupled with the bottle transparency contributed to the occasional difficulty in
identifying or seeing some bottles.
To better understand the overall bottle delivery, the distances between bottles must be
considered. Table 21 lists the number of gaps and their percentage of the total number of bottle gaps for
various ranges of bottle separation distances. As shown in Table 21, approximately 91 percent of the
bottle gaps are more than 2 inches. More than half the gaps are greater than 3 feet. The separation
distance required to avoid the air blast from sweeping adjacent bottles is not definitively known. CPRR
personnel report that approximately 2 inches is an adequate distance, and this was qualitatively
observed during the testing. With 91 percent of the gaps exceeding this separation distance, the
majority of the bottles appear to have been more than adequately separated. The average separation
distance was 5.1 feet with a standard deviation of 5.61. The maximum value was 61.7 feet, and the
minimum was 0. The >10 feet distance grouping in Table 21 shows many gaps far exceeding 10 feet,
skewing the mean distance between bottles.
43
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TABLE 20. COMPARISON OF VIDEO
VS FIELD BOTTLE COUNT, EXTENDED TESTS
Field Video
Bottle Type count count Difference
Natural HOPE 1 1
PVC 109 106
Clear PET 443 443
Green PET 132 132
Opaque HOPE 692 690
Total 1377 1372
0
-3
0
0
-2
-5
TABLE 21. BOTTLE SEPARATION DISTANCES
(CONVEYOR C5, EXTENDED TEST?)
Distance range Number
of Gaps Percentage
<=2"
>2"
>12"
>24"
>36"
>48"
>60"
>120
Total
117 8.5%
and<=12" 127 9.3%
and<=24" 169 12.3%
and<=36" 193 14.1%
and<=48" 149 10.9%
and <= 60" 134 9.8%
and <= 120" 292 21.3%
191 13.9%
1372
Cumulative
Percentage
8.5%
17.8%
30.1%
44.2%
55.0%
64.8%
86.1%
100.0%
44
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While some of the bottle separation distances are due to the presence of natural HOPE bottles in
the mix (which if properly recovered do not appear on conveyor C5 and therefore leave a gap), many are
due to the manner in which the feed conveyor extracts bottles from the feed bin and discharges onto the
singulating and presentation conveyors. The cleated feed conveyor discharges in distinct slugs rather
than in a continuous manner. If botties could be conveyed on conveyor C5 with a consistent 2-inch gap,
a maximum feed rate of approximately 285 bottles per minute could be achieved. Assuming 25 percent
of the entire mix is natural HOPE, the entire system would be capable of delivering approximately 380
bottles per minute.
The overall bottle feed rate for test 7 was 75 bottles per minute. This is approximately one fifth
of the theoretical maximum feed rate calculated above. Clearly the feed system was not capable of
delivering uniformly singulated bottles to the identification/separation stations at an average feed rate of
75 bottles per minute. Its delivery capabilities limited the throughput capacity of the system.
There was a general trend of relatively short periods of high delivery rates dispersed among
relatively long periods of average or low delivery rates. Table 22 lists the delivery rates for discrete short
time segments during the first five minutes of the test and compares them to the average feed rates for
bottles delivered to conveyor C5. The data show the irregular feed pattern containing spikes several
times greater than the average rate. This pattern arises from the batch method of remixing the bottles,
the removal of natural HOPE and other oversize bottles at the oversize station, and the slug feed
characteristic of the feed conveyor, i.e., with filled and unfilled cleats.
TABLE 22. BOTTLE DELIVERY RATES, EXTENDED TESTS
Average rate,
Bottle type bpm
PVC 4
Clear PET 17
Green PET 5
Opaque HOPE 29
Rate range,
bpm
2-18
18-90
4-60
6-90
Clear PET Station Mistakes--
Following the recording of the bottle type and delivery times, the video tape was viewed to
determine the types of recovery mistakes occurring at the clear PET station. Three general groupings of
recovery mistakes were used: miss, sweep, and incorrect recovery (reporting to the wrong station). A
miss can be the result of the failure of the sensor to detect or identify a bottle, or the failure of the air
blast to carry the bottle off the belt. A sweep is the simultaneous removal of an incorrect bottle with a
correct bottle. An incorrect recovery is the misidentification and removal of the wrong type of bottle.
45
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Table 23 lists the mistakes noted at the clear PET station. Included are the distances from the
previous bottle and to the following bottle to demonstrate whether the bottle was grouped or isolated. A
grouped bottle is considered to be one 2 inches or less from either the leading or to the trailing bottle.
Nearly one-half (29 out of 60) of the mistakes itemized in this table are associated with grouped bottles.
These are marked with an asterisk (*) following the bottle number. Therefore, approximately one-half of
the mistakes at the clear PET station are the result of poor bottle spacing.
Table 24 lists the ranges of separation distances for bottles presented to the clear PET station.
It considers both the distance to the previous bottle regardless of its type and the distance to the
following bottle regardless of its type and groups the bottle according to the lesser of the two distances.
From Table 24, it can be seen that 8 percent of the bottles presented to the clear PET station
were spaced 2 inches or less from adjacent bottles. Together with the data presented in Table 22, this
demonstrates that approximately 8 percent of the bottles presented to the clear PET station were
responsible for 50 percent of the mistakes at the clear PET station.
The tape analysis failed to account for a total of three recovery mistakes at the clear PET station,
as determined by the actual bottle counts (given in Appendix A). From the actual counts, it can be
reasoned that these three bottles consisted of one PVC bottle and two opaque HOPE bottles. These
three bottles correspond with three of the video rendering count mistakes listed in Table 20 and are
assumed to be the same bottles. The error in documenting the clear PET station mistakes using the
video tape analysis was 3 out of the 448 bottles reporting, or 0.67 percent.
Types of Identification/Separation Mistakes
Several different types of identification/separation mistakes were noted during the testing
program. Table 23 groups these into three classes (sweep, miss, and report to wrong station). The
conditions causing these mistakes vary, several of which are discussed herein.
Critical Distance - If a pair of bottles is not singulated properly so that a very small
distance separates them, they can be detected as one bottle by the optical "presence"
sensors, and can be identified as a clear PET bottle if the identification sensor reads the
clear air gap between the two bottles. CPRR personnel have determined that a gap of
approximately 2 inches or less can cause this type of error.
Deterioration of Bottle Surface - Severe abrasion or other deterioration of the bottle
surface was observed to cause clear and green PET to be viewed as opaque rather than
transparent.
Valley Effect - Although the testing was performed on whole, uncrushed bottles, the
paddle wheel for oversize bottle removal occasionally dented PET or opaque HOPE
bottles. If passed by the identification/separation station in an orientation such that the
bottle is deformed and part of the bottle is crushed below the identification sensor
height, the bottle can be identified as a clear PET bottle whether or not it is. Repetitive
use of the same bottles tended to increase the number of bottles with this condition.
When noted, deformed bottles were replaced with another uncrushed or undented bottle
of the same type.
Handle Effect - If opaque HOPE bottles pass by the identification/separation station in an
orientation where the handle opening is exposed to the sensor, the bottle can be
identified as a clear PET bottle in a manner similar to a critical distance mistake.
46
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TABLE 23. BOTTLE DELIVERY/RECOVERY ERRORS. CLEAR PET STATION ONLY
BOTTLE BOTTLE
NUMBER TYPE
28 Clear PET
120 Clear PET
211 Clear PET
324 * Clear PET
328 * Clear PET
364 Clear PET
388 * Clear PET
396 * Clear PET
438 Clear PET
495 Clear PET
550 Clear PET
587 * Clear PET
690 Clear PET
744 Clear PET
810 * Clear PET
937 Clear PET
1075 Clear PET
1186 * Clear PET
1198 * Clear PET
1199 Clear PET
1278 Clear PET
1281 Clear PET
272 Green PET
531 * Green PET
739 Green PET
747 Green PET
753 Green PET
950 Green PET
83 * Green PET
910 * Green PET
17 * Opaque HOPE
63 * Opaque HOPE
212 Opaque HOPE
378 * Opaque HOPE
508 * Opaque HOPE
509 * Opaque HOPE
530 » Opaque HOPE
729 Opaque HOPE
730 Opaque HOPE
782 * Opaque HOPE
830 Opaque HOPE
971 Opaque HOPE
1065 Opaque HOPE
1069 Opaque HOPE
1134 Opaque HOPE
1179 Opaque HOPE
1271 Opaque HOPE
1274 * Opaque HOPE
22 * Opaque HOPE
90 * Opaque HOPE
325 » Opaque HOPE
342 * Opaque HOPE
430 * Opaque HOPE
581 * Opaque HOPE
594 * Opaque HOPE
612 * Opaque HOPE
1007 * Opaque HOPE
1073 * Opaque HOPE
182 PVC
1163 PVC
ERROR CODE - DESCRIPTION
H - Clear PET bottle missed.
H - Clear PET bottle missed.
H - Clear PET bottle missed.
H - Clear PET missed - air jets fired & carried subsequent opaque HOPE.
H - Clear PET missed - very close to previous bottle.
H - Clear PET bottle missed.
H - Clear PET overlapped with a green PET and was missed.
H - Clear PET was lapped with an opaque HOPE and was missed.
H - Clear PET bottle missed.
H - Clear PET bottle missed.
H - Clear PET disrupted by previous PVC removal and was missed.
H - Clear PET bunched with another clear PET was missed.
H - Clear PET bottle missed.
H - Clear PET bottle missed.
H - Clear PET bottle missed.
H - Clear PET bottle missed.
H - Clear PET bottle missed.
H - Clear PET was butted with previous opaque HOPE bottle and was missed.
H - Clear PET was butted with previous opaque HOPE bottle and was missed.
H - Clear PET bottle missed.
H - Clear PET bottle missed.
H - Clear PET bottle missed.
R - Green PET reported to clear following a small jam on C5.
R - Green PET lapped with opaque HOPE and reported to clear PET station.
R - Green PET bottle reported to clear PET station.
R - Green PET reported to clear PET.
R - Green PET bottle reported to clear PET station.
R - Green PET bottle reported to clear PET station.
S - Swept into clear PET station with following clear PET bottle.
S - Green PET swept into clear PET with following clear PET bottle.
R - Opaque HOPE reported to clear PET station.
R - Removed incorrectly by clear PET station.
R - Opaque HOPE bottle reported to clear PET station - "Handle Effect".
R - PVC station fired on opaque HOPE & it bounced into clear PET station.
R - Opaque HOPE bottle reported to clear PET station.
R - Opaque HOPE bottle reported to clear PET station.
R - Opaque HOPE lapped with Green PET and reported to Clear PET station.
R - Opaque HOPE bottle reported to clear PET.
R - Opaque HOPE bottle reported to clear PET.
R - Opaque HOPE bottle reported to clear PET station.
R - Opaque HOPE bottle reported to clear PET station.
R - Opaque HOPE bottle reported to clear PET station.
R - Opaque HOPE bottle reported to clear PET station, knocked by PVC blast
R - Opaque HOPE bottle reported to clear PET station.
R - Opaque HOPE bottle reported to clear PET station.
R - Opaque HOPE reported to clear PET station - "Handle Effect".
R - Opaque. HOPE bottle reported to clear PET station.
R - Opaque HOPE bottle reported to clear PET station.
S - Opaque HOPE swept to clear PET station with following clear PET.
S - Swept into clear PET station with following clear PET bottle.
S - Opaque HOPE swept into clear - note preceding clear was not caught.
S - Opaque HOPE swept into clear PET station with following clear PET.
S - Opaque HOPE swept into clear PET with following clear PET bottle.
S - Opaque HOPE swept into clear PET with following clear PET bottle.
S - Small opaque HOPE swept into clear PET with following clear PET.
S - Opaque HOPE swept into clear PET with following clear PET bottle.
S - Opaque HOPE swept into clear PET with following clear PET bottle.
S - Small opaque HOPE swept into clear PET with following clear PET.
R - PVC bottle was missed and reported to clear PET station.
R - PVC bottle missed and reported to clear PET station.
FT- IN TO
PREVIOUS
BOTTLE
15-08
10-03
3-06
0-00
0-01
5-09
1-03
0-00
7-03
6-07
0-05
0-00
12-08
1-00
1-07
6-10
2-11
0-00
0-00
1-05
2-04
6-09
1-10
0-00
1-07
5-09
18-10
4-06
0-03
1-06
1-02
0-02
4-08
0-01
0-00
0-00
6-05
3-11
3-06
0-00
0-05
3-03
0-05
5-03
4-05
3-11
3-09
0-07
0-07
13-07
11-08
0-00
28-00
4-05
1-01
7-05
2-04
0-10
9-01
3-01
FT- IN TO
FOLLOWING
BOTTLE
3-11
4-02
4-08
11-08
1-10
8-03
0-00
1-01
5-11
2-06
4-02
5-08
3-03
10-08
0-00
23-04
3-00
6-02
1-05
7-07
5-08
5-00
0-04
14-10
4-06
14-11
4-09
2-01
0-00
0-00
0-00
5-00
8-10
o-oo
0-00
1-10
0-00
3-06
1-01
2-01
15-04
6-06
2-04
0-09
7-04
4-03
2-11
0-00
0-00
0-00
0-00
0-03
0-00
0-00
0-00
0-00
0-00
0-00
2-03
6-01
Distances assume conveyor C5 speed of 330 feet per minute and an average bottle length of 12 inches.
Error codes: S = sweep, H = miss, R = report to wrong station.
All delivery data transcribed from a video tape of the clear PET and PVC stations.
Only the errors visible at the clear PET are included.
Bottles marked with an asterisk <*) are located within 2 inches of an adjacent bottle.
47
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TABLE 24. MINIMUM SEPARATION DISTANCES FOR EACH BOTTLE
PRESENTED TO CLEAR PET STATION
Distance range
<=2"
>2" and<=12"
>12" and<=24"
> 24" and <= 36"
> 36" and <= 48"
>48" and<=60"
>60" and <= 120"
> 120"
Total
Number
100
110
150
179
142
123
270
176
1250
Percentage
8.0%
8.8%
12.0%
14.3%
11.4%
9.8%
21.6%
14.1%
Cumulative
Percentage
8.0%
16.8%
28.8%
43.1%
54.5%
64.3%
85.9%
100.0%
48
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SECTION 6
COMMERCIAL POTENTIAL
As previously stated, the Rutgers system was designed to be a proof-of-concept pilot-scale
process rather than a commercial-scale model. Its development emphasized the bottle identification
aspects rather than the material handling aspects of the system. These facts coupled with the lack of
the most recent PVC detection equipment complicates an evaluation of the system's true commercial
potential. Significant design changes would be required in order to upgrade the equipment to
commercial status and to improve the overall system performance so that all products meet
commercially acceptable contamination limits. Process design changes that may enhance the Rutgers
bottle sorting system's performance are discussed below.
PILOT SYSTEM DESIGN COMMENTS AND SUGGESTED MODIFICATIONS
Conveyor Speeds
Comment: The conveyor speeds are not cascaded. Normally, each conveyor in a series is
designed to operate at a speed slightly above that of the conveyor immediately
preceeding it. In the CPRR system, conveyor C3 serves as a feed buffer and as such
operates at a higher speed than the subsequent conveyor, C4a. As a result, containers
separated by the dual feed chute that feeds C3 are often brought back together at the
transition from C3 to C4a.
Modification: Proper cascading of the conveyor speeds (i.e., progressively increasing speeds for
downstream" conveyors) would improve bottle singulation by allowing both the dual feed
chute and conveyor C4a to assist in the singulation process.
Dual Feed Chute
Comment: The dual feed chute is not properly sized for the range of bottle sizes tested. The chute
clearances are such that large bottles, particularly large opaque HOPE and 3-liter soda
bottles, frequently became jammed inside the chute. Such jams, when cleared, can
result in slugs of containers that are insufficiently singulated for the
identification/separation stations to process accurately.
Modification: Enlarging the feed chute to accommodate the range of bottle sizes anticipated would
eliminate most feed chute jams.
49
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Conveyor C3 Skirting
Comment: The skirting on conveyor C3 is too narrow for the sizes of bottles tested. Conveyor C3
has an 18-inch wide belt, yet the skirting width is set at 10 inches, nearly exactly the
length of a 1-liter soda bottle. Bottles occasionally became jammed perpendicular to the
skirting, and when cleared, sometimes resulted in slugs of improperly singulated
containers.
Modification: A vertical tapering of the conveyor skirting would eliminate most jams at this location.
Conveyor C3 Diverters
Comment: The flexible metal diverter strips were mounted on alternating sides of conveyor C3 to
direct the bottles in a zig zag path while being transported by conveyor C3. This was
done to help singulate the bottles. However, these diverters often served to slow the
movement of bottles. When returning to their resting position after bending to allow a
bottle to pass, they often impacted a trailing bottle, momentarily halting it completely,
thereby reducing the spacing between it and trailing bottles.
Modification: These diverters should be removed completely as they did little to improve bottle
presentation.
Paddle Wheel Construction
Comment: The paddle wheel, as constructed, was unable to function for extended operation. The
rubber flaps used to eject the bottles repeatedly broke free from the aluminum angle
used to hold them to the pulley. The rubber flaps were fastened to the angle with five
small diameter bolts, providing little bearing area at the connection. The flaps flexed
with each impact, and the soft rubber eventually failed at the connections. This failure
was the major source of the downtime experienced during the extended test series.
Modification: Suggestions include using large diameter flat washers between each bolt head and the
rubber flap, or a continuous section of flat stock under the bolt heads to provide a
continuous bearing surface. The modifications implemented following each flap failure
were adequate to ensure adequate performance of that flap during subsequent
operation. However, more than one flap failed during the tests.
Paddle Wheel Fastening
Comment: The paddle wheel was held in place with C-clamps to allow adjustment of the clearance
to enable the "target" oversize bottle (i.e., natural HOPE containers) to be diverted from
the material stream. Fastened in this manner, the paddle wheel was subject to
movement from vibration and impact.
Modification: Providing a more permanent and stable connection of the unit to the feed conveyor
frame would eliminate the problem.
50
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Conveyor C4 (a.b. and c) Belting
Comment:
Modification:
Conveyor C4 (a, b, and c) uses V-belts in lieu of solid .rubber belting. Bottle caps
liberated during processing occasionally became jammed under the V-belts,
occasionally causing the belts to disengage from the pulleys. This was the cause of one
major downtime during the first week of testing.
Use of rubber belting in place of V-belts would improve the mechanical operation of this
unit.
Conveyor C4 Construction
Comment: The three overlapping segments of conveyor C4 could not properly singulate the bottles
under all feed conditions. Very small light weight containers such as the small opaque
HOPE "pill" bottles often could not be adequately separated from the container
immediately following them. Their short length did not sufficiently span two segments of
conveyor C4, and thus they could not be pulled away from closely following containers.
Modification: The separation efficiency of this unit could be improved by extending the length of this
section and including more overlapping sections of narrower width.
Conveyor C5 Diverters
Comment: The flexible metal cliverters added to conveyor C5 after the first week of testing were
effective in aligning PVC bottles, but often had the opposite effect on PET soda bottles if
fed base cup first. When fed in this orientation, the bottles, upon impact with the
diverters, would often rotate vertically on the rounded portion of the bottle just below the
neck. Once tipped, they would bounce and often loose their parallel alignment with
conveyor C5, and therefore would not be presented properly to the sensors.
Modification: Use of the Asoma VS-2 PVC detector would eliminate the need for these diverters.
They were added to assist in aligning the bottles along the conveyor skirting on which
the PVC sensor was mounted. With the Asoma VS-2 unit mounted underneath the
conveying surface, it would not be necessary to pass the bottles close to a
vertically-mounted sensor. The PET stations do not require a close bottle/sensor
alignment since the optical sensors used for PET detection are not sensitive to distance
when used in bottle sorting applications.
Control of Bottle Feed Rate
Comment: As shown previously, the feed rate varied considerably throughout the tests. With the
exception of conveyor C2, all conveyors operate at the same speed regardless of the
desired bottle feed rate. This is because the sensor/air jet timing and air blast duration
are set for a specific presentation conveyor speed. Bottle feed rates are set by adjusting
the speed of conveyor C2. This conveyor discharges in slugs, a slug consisting of the
contents of one cleat. By slowing or speeding up this conveyor, the time between slugs
is either increased or decreased. What this means is that a slug of bottles is presented
to the identification/separation equipment at a uniform rate regardless of bottle feed rate.
The contents of a typical slug did not appear to change as a result of changes in the feed
rate, and operation of the identification/separation equipment is not affected by the gaps
between slugs.
51
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Speed control in the manner used by the CPRR can affect bottle recovery only if the
slugs are delivered with such frequency that the ability of conveyors C3 and C4 to
singulate the slugs of bottles is exceeded, or by magnifying the consequences of a feed
chute jam. Recovery efficiencies were noted to be relatively unaffected by changes in
feed rate within the range investigated. The time between slug discharges varied
depending on the composition of the feed material in each cleat. Many cleats contained
mostly or only natural HOPE bottles and therefore contributed little or nothing to
conveyor C3. Fallback of opaque HOPE bottles often knocked other bottles out of their
cleat, contributing to a sparse feed for that cleat.
Modification: The feed rate could be evened out by employing a two bin feed system. Under such a
system, mixed bottles would be fed in the same manner as the Rutgers system except
that instead of discharging directly onto the conveyor system feeding the sensors, all
bottles that passed the oversize station would drop into a second metering bin with
sufficient buffer capacity. The first feed conveyor would be equipped with fairly short
cleats similar to those used by the Rutgers system so that oversize bottles could be
removed by the mechanical paddle wheel. The bottles in the second feed bin could be
fed using a variable speed conveyor with deep cleats to eliminate fallback and to ensure
a constant supply of bottles to the conveyor system. Proper adjustment of conveyor
speeds and lengths will enable the bottles to be more uniformly presented to the
sensors. This step should result in a significantly increased throughput without affecting
bottle recovery.
PVC Recovery
Comment: Use of the improved Asoma VS-2 PVC sensor system should significantly improve PVC
recoveries and therefore decrease PVC contamination. Bottles are typically presented
to this sensor via a sloping plate and not with a belt conveyor as with the first generation
XRF detector. The overall system configuration would need to change to accommodate
this feed arrangement.
Modification: A multiple pass system will improve recovery by allowing more than one opportunity to
detect and remove target products. For example, additional PVC sensors may be
required to clean up certain product streams if primary PVC recovery is insufficient to
meet product purity requirements. Use of the new Asoma VS-2 sensor may eliminate
the need for secondary PVC clean-up, however.
EQUIPMENT COST ESTIMATE
As previously discussed, because of the extensive modifications necessary to upgrade the Rutgers
system to commercial level, a commercial scale capital or operating cost analysis is not justified. Rather,
it may be useful to establish a capital cost for the current configuration thereby providing a baseline
against which to measure the cost of future changes. Table 25 presents the equipment costs for the
Rutgers system as constructed. No installation costs are included, nor are the costs of such items as
motor starters, power wiring, gaylord boxes, spare parts, and the air compressor. It should be noted that
the Asoma I PVC detector is no longer in production and has been replaced by a newer model, the cost
of which may be different from that included in this estimate.
52
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TABLE 25. EQUIPMENT COSTS
Component
Number Unit Cost Total Cost
PVC Detector
Optical Station
Includes sensors, air nozzles, hose
Infeed System
Includes feed hopper, infeed conveyor,
paddle and kick wheels, dual
discharge chute, and oversize chute
Conveyor C4a,b,c
Conveyors C3, C5, C6, C7
1 $40,000 $40,000
3 $500 $1,500
$5,000
$5,000
$3,000
$5,000
$5,000
$3,000
$54,500
EXISTING COMMERCIAL SYSTEMS
There are currently three existing commercial systems for the identification and separation of
individual resins in a mixed plastics stream^A^. These systems are briefly described below for
background comparison purposes. All three report container recoveries and throughput rates in excess
of those found for the Rutgers system, and all reportedly can accommodate crushed bottles. These
manufacturer claims, however, have not been independently verified.
The commercial systems have encountered some processing problems (5). Air jets are typically
used to remove the detected bottle from the stream, and flattened bottles can pose removal problems in
that they can act as an airfoil and actually become forced down on the conveyor belt instead of being
blown off the belt. Color sensors can mistakenly read the color of the labels or the container residue.
Bale breaking and subsequent bottle singulation (if required) can be difficult, especially with bales of
various sizes and bottles of varying degrees of deformation.
Magnetic Separation Systems. Inc. - BottleSort System
The basic Magnetic Separation Systems (MSS) system uses different intensities of light to
distinguish clear bottles consisting of PET and PVC, translucent bottles consisting of HOPE milk and
juice containers, polypropylene (PP) syrup and ketchup bottles, and opaque bottles consisting of
detergent and shampoo bottles. Air jets are used to remove the detected bottles from the conveyor belt.
Further resin separation can be accomplished using additional modules consisting of an Asoma VS-2
PVC detector, a computer-controlled HOPE color detector, an optical PET color sensor, and an optical
PP sensor. The color detectors employ computer software to identify seven bottle colors, ignoring the
labels and residue contamination. Each bottle is scanned by an array of 16 sensors which make 5,300
readings per second to determine the bottle type.
The base separation system was installed at Eaglebrook's Chicago facility in January of 1992,
and the color separation system was installed in September of 1992. Four parallel sorting lines are
claimed to be able to identify and separate 8 to 12 bottles per second (120 - 180 bottles per minute per
line), providing a total capacity of 5,000 pounds per hour. Problems have been experienced with the
feed system, and manual inspection was used to enhance the PVC removal. MSS claims that the basic
three-way separation system can achieve a 96 to 99 percent resin separation and that over 99 percent of
the PVC bottles can be capturedW
53
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National Recovery Technologies. Inc. - VinvlCvcle System
The National Recovery Technologies (NRT) system uses an electromagnetic sensor that
separates PVC bottles from a mixed stream of whole or crushed HOPE, PET, and PVC bottles. The
mixed stream is passed down a slide. Air jets mounted below the slide are used to blow detected PVC
bottles over a partition. Undetected bottles fall on the opposite side of the partition. The air jets cannot
necessarily remove only the detected PVC bottle as adjacent bottles can be swept over the partition with
the PVC. Hence this system produces two product streams, one consisting of mixed bottles and one
PVC-rich stream, it is claimed that the bottles need not be oriented or singulated before being presented
to the detector.
NRT currently has three models, the highest production model is reportedly capable of
processing 10 bottles/second or 4500 pounds/hour, and yields a product with less than 50 parts per
million (ppm) PVC contamination.(4) NRT guarantees a PVC contamination limit of 50 ppm if the PVC
content of the infeed mixed stream does not exceed 1 percent. The PVC recovery is reportedly greater
than 99.4 percent, with 100 percent PVC removal possible with two passes. According to The Vinyl
Institute, 18 NRT systems have been installed worldwide/2^
Automation Industrial Control - PolySort System
The Automation Industrial Control (AIC) system uses infrared spectrographic analysis of light
transmitted through singulated bottles to distinguish containers by resin type and color.w Air jets
segregate the detected bottles into polypropylene, PVC, natural HOPE, colored HOPE, green PET, and
clear PET product streams. Two sensors read the bottle and the information is processed in a 486-chip
microprocessor. A time of 19 milliseconds is required to determine the bottle type and color. Actual
processing rates are reported to be 700 - 800 pounds per hour @). The system reportedly can process
either compacted or uncrushed bottles. Unread bottles remain on the belt and can be recycled through
the system or discarded. The first commercial system was installed in 1992 at the North American
Plastics Recycling Corporation plant in Ft. Edward, NY. No performance information is available at this
time.
54
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REFERENCES
1. wTe Corporation. MITE Program for Automatic Sortation Process for Post-Consumer Plastic
Containers, Draft Quality Assurance/Quality Control Project Plan, 1992.
2. Gottesman, R.T. Vinyl Recycling in the United States. The Vinyl Institute.
3. Lipson C. and N.J. Sheth. Statistical Design and Analysis of Engineering Experiments.
McGraw-Hill Book Company, NY, 1973.
4. Schut, J.H. Automatic Resin & Color Sorting Proves a Boon to Recyclers, Technology News,
September 1992. pp. 15-19.
5. Powell, J. Automated Plastic Bottle Sorting: An Emerging Technology, Resource Recycling,
August 1992. pp. 62-69.
6. Personal communication between D. Kirk and C. McCourt.
55
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APPENDIX A
TEST DATA AS COLLECTED
MIXED COMPOSITION 2,000 BOTTLE EXTENDED TESTS
56
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TABLE A-1. DATA FOR MIXED FEED 2,000 BOTTLE TEST
AT 60% FEED CONVEYOR SETTING
A-1.1 TEST 1
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
Station 1
Station 2
Station 3
Station 4
Station 5
Station
Station
Total
Nat
- Natural HOPE
- PVC
- Clear PET
- Green PET
HOPE
479
- Opaque HOPE
- Unfed
- Spi I lage
15
494
PVC
1
93
10
2
1
4
1
112
COMPONENT
Clear PET Green PET
3
3
424
13
4
9
456
2
7
121
8
5
1
144
DATE: 10/07/92
DURATION: 27.0 minutes
FEED RATE: 71 BPM
Opaque HOPE Total
42
11
30
8
639
36
2
768
525
109
471
144
652
69
4
1974
Observations:
Noted that
length of
Four jams
bottles can jam sideways on conveyor C3
a 1 liter PET bottle.
were caused
Three PVC bottles were
ended up in the clear
The fallback from the
25, and 16
The number
of oversize
by PET
bottles, and
detected and blown
PET station.
infeed
chute
conveyor was
pass-through
10 jams
- the skirting
were caused by
at the PVC station but
noted as
width is
nearly identical to
the
HOPE bottles.
failed to
fallback occurrences per
occurrences were noted
oer minute
enter the
minute:
: 11, 12,
chute. They
13, 18, 28
and 12.
A- 1.2 TEST 2
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
DATE:
DURATION:
FEED RATE:
10/07/92
28.0 minutes
69 BPM
COMPONENT
Nat HOPE
Station 1 - Natural HOPE
Station 2 - PVC
Station 3 - Clear PET
Station 4 - Green PET
Station 5 - Opaque HOPE
Station - Unfed
Station - Spillage
Total
Observations:
Four jams were noted.
479
15
494
PVC Clear PET
1 4
106 1
5 427
15
4
2
3
112 456
Green PET
1
1
6
117
13
6
144
Opaque HOPE
37
7
34
9
663
17
1
768
Total
522
115
472
141
680
40
4
1974
Paddle wheel lost a ruber paddle during the test. It was repaired following the test -
approximately one hour required to repair.
Clear was firing on opaque
HOPE and was
The sweeping effect is very noticeable.
spaced.
adjusted during the
Two bottle will be
test.
removed as one
if they are
closely
57
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TABLE A-1. CONTINUED
A- 1.3 TEST 3
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
Station 1 -
Station 2 -
Station 3 -
Station 4 -
Station 5 -
Station
Station
Total
Observations
Natural HOPE
PVC
Clear PET
Green PET
Opaque HOPE
Unfed
Spillage
:
Video taped this test -
Time for one revolution
Hat HOPE
473
1
20
494
green PET station
of Conveyor C5 is
PVC
4
99
5
4
112
COMPONENT
Clear PET
7
9
409
15
3
8
5
456
Green PET
2
3
2
125
8
4
144
DATE: 10/07/92
DURATION: 28.0 minutes
FEED RATE: 69 BPH
Opaque HDPE
50
7
22
8
664
15
2
768
Total
536
118
438
153
675
47
7
1974
only.
7.5 seconds.
A-1. 4 TEST 4
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
DATE:
DURATION:
FEED RATE:
10/07/92
27.6 minutes
70 BPM
COMPONENT
Nat HDPE
Station 1 - Natural HDPE 481
Station 2 - PVC
Station 3 - Clear PET
Station 4 - Green PET
Station 5 - Opaque HDPE 2
Station - Unfed 11
Station - Spillage
Total 494
Observations:
PVC
1
100
6
4
1
112
Rubber flap on paddle wheel came loose and test
minutes, 45 seconds required to remove flap.
Video taped the clear PET and the
Eleven jams were noted.
Three PVC bottles were undetected
Two PVC bottles bounced back from
PVC stations.
Clear PET Green PET
2
5
415
24
5
3
2
456
was halted. Flat
because of inproper positioning
the PVC chute
Sweeping effect carried opaque HDPE into clear
, one ended up in
PET.
2
4
122
14
2
144
Opaque HDPE
47
6
23
24
655
13
768
was removed and test
on the
conveyor.
Total
533
111
448
174
676
30
2
1974
resumed. 2
clear PET, one in opaque HDPE.
A-1. 5 TEST 5
FEED: 2,000 MIXED BOTTLES
" SPEED: 60%
Station 1 - Natural HDPE
Station 2 - PVC
Station 3 - Clear PET
Station 4 - Green PET
Station 5 - Opaque HDPE
Station - Unfed
Station - Spillage
. Total
Cbservations:
!2 jams were noted.
Nat HDPE
471
1
20
2
494
Another rubber paddle was lost - test
PVC
3
104
4
1
112
was not
COMPONENT
Clear PET
4
2
417
20
1
10
2
456
halted.
Green PET
3
2
2
124
10
2
1
144
DATE: 10/08/92
DURATION: 28.0 minutes
FEED RATE: 69 BPM
Opaque HDPE
43
2
22
13
669
18
1
768
Total
524
110
441
161
681
51
6
1974
58
-------
TABLE A-1. CONTINUED
A- 1.6 TEST 6
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
Nat HDPE
Station 1 - Natural HDPE 459
Station Z - PVC
Station 3 - Clear PET
Station 4 - Green PET
Station 5 - Opaque HDPE 3
Station - Unfed 32
Station - Spillage
Total 494
Observations:
DATE: 10/08/92
DURATION: 26.9 minutes
FEED RATE: 70 BPM
PVC
97
6
3
1
5
112
COMPONEN1
Clear PET
3
6
397
26
6
17
1
456
Two paddle wheel flaps failed on separate occasions. Both
removed, and the test resumed.
5 jams were noted.
Infeed conveyor fallback counts per
Oversize chute returns per minute:
minute: 30,
12, 12.
31, and 37
Green PET
1
1
4
118
15
5
144
times the test
.
Opaque HDPE
52
4
14
12
654
31
1
768
was halted, the
Total
515
108
421
159
679
90
2
1974
flap
A-1. 7 TEST 7
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
Nat HDPE
Station 1 - Natural HDPE 460
Station 2 - PVC
Station 3 - Clear PET
Station 4 - Green PET
Station 5 - Opaque HDPE 1
Station - Unfed 33
Station - Spillage
Total 494
Observations:
Clear PET sensor adjusted during test.
DATE: 10/08/92
DURATION: 25.3 minutes
FEED RATE: 75 BPM
PVC
1
102
3
4
1
1
112
Infeed conveyor fallback counts per minute: 36,
Oversize chute returns per minute: 10,
9, and,
COMPONENT
Clear PET
4
14
407
18
4
6
3
456
30, and 30.
22.
Green PET
4
3
8
107
14
6
2
144
Opaque HDPE
51
4
30
19
639
23
2
768
Total
520
123
448
148
658
69
8
1974
A-1. 8 TEST 8
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
DATE: 10/08/92
DURATION: 26.5 minutes
FEED RATE: 73 BPM
COMPONENT
Station 1 -
Station 2 -
Station 3 -
Station 4 -
Station 5 -
Station
Station
Total
Observations
Natural HDPE
PVC
Clear PET
Green PET
Opaque HOPE
Unfed
Spillage
:
Two PVC bottles reported
17 jams were
A PVC bottle
station.
noted.
Nat HDPE
471
3
?.
3
15
494
to clear PET
and a natural HDPE bottle
PVC
101
7
4
112
station
Clear PET Green PET
1
6
424
14
5
5
1
456
because of a
were observed to be
1
4
123
13
3
144
jam.
Opaque HOPE
45
8
33
15
659
8
768
ejected simultaneously at the
Total
517
119
470
156
680
31
1
1974
clear PET
59
-------
TABLE A-1. CONTINUED
A- 1.9 TEST 9
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
Station 1
Station 2
Station 3
Station 4
Station 5
Station
Station
Total
- Natural HOPE
- PVC
- Clear PET
- Green PET
- Opaque HOPE
- Unfed
- Spillage
Nat HOPE
475
1
2
1
14
1
494
PVC
95
9
5
2
1
112
COMPONENT
Clear PET
5
2
411
30
5
2
1
456
Green PET
4
1
6
112
18
3
144
DATE: 10/08/92
DURATION: 26.1 minutes
FEED RATE: 74 BPM
Opaque HOPE
40
4
69
9
631
13
2
768
Total
524
103
495
158
657
32
5
1974
Observations:
Eleven jams were noted.
Of the 69
opaque HOPE bottles in the
clear PET
station, 22
were small bottles.
A-1. 10 TEST 10
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
Station 1 - Natural HOPE
Station 2 - PVC
Station 3 - Clear PET
Station 4 - Green PET
Station 5 - Opaque HOPE
Station - Unfed
Station - Spillage
Total
Observations:
Sixteen jams were noted.
Nat HOPE
460
2
5
27
494
Clear PET optical sensors adjusted
Appears that large PVC bottles are
detected.
PVC
99
6
3
1
3
112
during the
not passed
COMPONENT
Clear PET
5
7
421
4
2
15
2
456
test.
quiescently past
DATE: 10/09/92
DURATION: 26.0 minutes
FEED RATE: 73 BPM
Green PET Opaque HOPE
2
3
1
120
12
6
144
the PVC
36
5
18
17
670
22
768
detector and often
Total
503
114
446
146
690
73
2
1974
are not
A-1. 11 TEST 11
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
Station 1 - Natural HOPE
Station 2 - PVC
Station 3 - Clear PET
Station 4 - Green PET
Station 5 - Opaque HOPE
Station - Unfed
Station - Spillage
Total
Observations:
Nat HOPE
470
1
1
7
15
494
Ten jams noted: three at the C3/C4
in the feed chute.
PVC
1
102
4
3
1
1
112
transition,
COMPONENT
Clear PET Green PET
3
10
390
42
5
4
2
456
three on conveyor
2
125
13
4
144
C3, two
DATE: 10/09/92
DURATION: 25.8 minutes
FEED RATE: 75 BPM
Opaque HOPE
37
9
10
16
678
17
1
768
on conveyor C4,
Total
511
122
406
187
704
41
3
1974
and two
60
-------
TABLE A-1. CONTINUED
A-1. 12 TEST 12
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
Mat HOPE
Station 1 - Natural HOPE 477
Station 2 - PVC 1
Station 3 - Clear PET
Station 4 - Green PET 1
Station 5 - Opaque HOPE 5
Station - Unfed 10
Station - Spillage
Total 494
Observations:
DATE: 10/09/92
DURATION: 26.0 minutes
FEED RATE: 75 BPH
PVC
1
100
5
6
112
COMPONENT
Clear PET
4
7
417
17
5
5
1
456
Green PET
2
2
125
14
1
144
Opaque HDPE
37
6
12
694
19
768
Total
519
116
436
149
718
34
2
1974
Seven jams noted: two in the feed chute, two at the C3/C4 transition, and three on conveyor C3.
The flexible metal diverters on conveyor C3 appear to do little good and perhaps slow down the
bottles, reducing the spacing achieved by the dual discharge chutes.
A- 1.13 TEST 13
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
Station 1 -
Station 2 -
Station 3 -
Station 4 -
Station 5 -
Station
Station
Total
Observations
Natural KDPE
PVC
Clear PET
Green PET
Opaque HDPE
Unfed
Spillage
:
Seven Jams noted: two in
Small opaque HDPE bottles
singulating conveyor C4.
One large PVC noted to be
Nat HDPE
486
4
4
494
the feec
PVC
97
10
4
1
112
chute, and
do not have enough
too far
COMPONENT
Clear PET Green PET
12
421
10
3
10
456
five on conveyor C3
Length to be pulled
1
3
128
8
4
144
,
away from
DATE: 10/09/92
DURATION: 25.3 minutes
FEED RATE: 76 BPM
Opaque HDPE Total
22
8
28
20
663
25
2
768
trailing
508
118
462
162
679
43
2
1974
bottles by
the
from the sensor to be detected.
A-1. 14 TEST 14
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
DATE:
DURATION:
FEED RATE:
10/09/92
25.3 minutes
76 BPM
COMPONENT
Nat HDPE PVC Clear PET Green PET Opaque HDPE Total
Station 1 - Natural HDPE
Station 2 - PVC
Station 3 - Clear PET
Station 4 - Green PET
Station 5 - Opaque HDPE
Station - Unfed
Station - Spillage
Total
Observations:
470
5
19
494
97
10
5
112
3
4
432
4
5
. 6
2
456
2
3
127
8
4
144
26
7
17
16
675
27
768
499
110
462
152
693
56
2
1974
Four jams on conveyor C3 noted.
Grreen and clear PET sensors were
A group of two PVC and one
other PVC went undetected.
Flexible metal diverter on
station.
clear
adjusted during the
PET were observed - 1
test
PVC
-
and 1 clear
conveyor C5 caused an opaque HDPE bottle to
PET removed at
be removed at
PVC station.
the PVC
61
-------
TABLE A-1. CONTINUED
A-1. 15 TEST 15
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
Station 1 - Natural HOPE
Station 2 - PVC
Station 3 - Clear PET
Station 4 - Green PET
Station 5 - Opaque HOPE
Station - Unfed
Station - Spillage
Total
Observations:
Five jams noted: three
Flexible metal diverters
Nat HOPE
466
2
1
5
20
494
on conveyor C3,
on conveyor C5
PVC
2
95
8
6
1
112
COMPONENT
Clear PET Green PET
3
430
11
3
7
2
456
one on conveyor C4, and
disorient PET bottles.
3
5
115
14
6
1
144
one in the
DATE: 10/09/92
DURATION: 24.4 minutes
FEED RATE: 79 BPM
Opaque HDPE
28
1
15
10
702
10
2
768
feed chute.
Total
496
104
459
142
725
43
5
1974
62
-------
APPENDIX B
EXTENDED TEST RESULTS, OUTLIERS NOT INCLUDED
MIXED COMPOSITION 2,000 BOTTLE EXTENDED TESTS
63
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APPENDIX C
BOTTLE COUNTS AND WEIGHT PERCENTAGES
MIXED COMPOSITION 2,000 BOTTLE EXTENDED TESTS
69
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TABLE C-1. BOTTLE COUNTS AND WEIGHT PERCENTAGES FOR
MIXED FEED 2,000 BOTTLE TEST AT 60% FEED CONVEYOR SETTING
C-1.0
Bottle Type
Average Bottle Weight
Natural HOPE Product
PVC Product
Clear PET Product
Green PET Product
Opaque HOPE Product
ALLOWABLE
Nat HOPE
64 grams
100.00
5.00
5.00
5.00
5.00
WEIGHT PERCENT CONTAMINATION LIMITS
PVC
59 grams
2.00
100.00
0.00
0.00
2.00
Clear PET
71 grams
2.00
0.00
100.00
10.00
2.00
Green PET
78 grams
2.00
0.00
1.00
100.00
2.00
Opaque HOPE
101 grams
1.00
5.00
5.00
5.00
100.00
Maximum combined opaque and natural HOPE contamination in either clear PET, green PET, or PVC is 5%.
Maximum combined PVC, clear PET, and green PET contamination in either natural or opaque HOPE is 2%.
Maximum combined PET contamination in PVC is 0%.
C-1.1 TEST 1
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
Nat HOPE
No./Wt %
Natural HOPE Product 479/87.17%
PVC Product
Clear PET Product
Green PET Product
Opaaue HOPE Product
DATE:
DURATION:
FEED RATE:
COMPONENT
PVC Clear PET Green PET Opaque HOPE
No./Wt % No./Wt % No./Wt % No./Wt %
M 0.17% 3/ 0.61% 42/12.06%*
93/78.76% 3/ 3.06%* 2/ 2.24%* 11/15.95%*
10/ 1.72%* 424/87.84% 7/ 1.59%* 30/ 8.84%*
21 1.05%* 13/ 8.18% 121/83.62% 8/ 7.16%*
M 0.09% 4/ 0.43% 8/ 0.95% 639/98.52%
10/07/92
27.0 minutes
71 BPM
Total
No./Wt %
525 /100% 1*
109/100% 3*
471 /100% 3*
144/100% 2*
652/100%
C-1. 2 TEST 2
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
Nat HOPE
No./Wt %
Natural HOPE Product 479/88.06%
PVC Product
Clear PET Product
Green PET Product
Opaque HOPE Product
DATE:
DURATION:
FEED RATE:
COMPONENT
PVC Clear PET Green PET Opaque HOPE
No./Wt % No./Wt % No./Wt % No./Wt %
1/ 0.17% 4/ 0.82% M 0.22% 37/10.73%*
106/87.96% M 1.00%* 1/ 1.10%* 71 9.94%*
S/ 0.85%* 427/87.84% 6/ 1.36%* 34/ 9.95%*
15/ 9.59% 117/82.22% 9/ 8.19%*
4/ 0.42% 13/ 1.49% 663/98.10%
10/07/92
28.0 minutes
69 BPM
Total
No./Wt %
522/100% 1*
115/100% 3*
472/100% 3*
141 /100% 1*
680/100%
C-1. 3 TEST 3
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
Nat HOPE
No./Wt %
Natural HOPE Product 473/83.60%
PVC Product
Clear PET Product
Green PET Product 1/ 0.54%*
Opaoue HOPE Product
DATE:
DURATION:
FEED RATE:
COMPONENT
PVC Clear PET Green PET Opaque HOPE
No./Wt % No./Wt % No./Wt % No./Wt %
4/ 0.65%* 7/ 1.37%* 2/ 0.43% 50/13.95%*
99/78.71% 9/ 8.61%* 3/ 3.15%* 7/ 9.53%*
5/ 0.93%* 409/91.57% 2/ 0.49% 22/ 7.01%*
4/ 1.98%* 15/ 8.93% 125/81.77% 8/ 6.78%*
3/ 0.31% 8/ 0.92% 664/98.77%
10/07/92
28.0 minutes
69 BPM
Total
No./Wt %
536*/100% 4*
118/100% 3*
438/100% 2*
153/100% 3*
675/100%
Excessive contamination indicated by *.
Total column excessive contamination notation indicates the number of contaminants (ex. 3*
70
-------
TABLE 0-1. CONTINUED
C-1.4 TEST 4
FEED: 2.000 MIXED
SPEED: 60%
BOTTLES
Nat HOPE
No./Wt %
Natural HOPE Product 481/85.78%
PVC Product
Clear PET Product
Green PET Product
Opaque HOPE Product 21 0.19%
PVC
No./Wt %
M 0.16%
100/85.99%
6/ 1.09%*
4/ 1.70%*
COMPONENT
Clear PET
No./Wt %
21 0.40%
5/ 5.17%*
415/90.79%
24/12.28%*
5/ 0.52%*
Green PET
No./Wt %
2/ 0.43%
4/ 0.96%
122/68.56%
14/ 1.61%
DATE:
DURATION:
FEED RATE:
Opaque HOPE
No./Wt %
47/13.23%*
6/ 8.83%*
23/ 7.16%*
24/17.46%*
655/97.67%
10/07/92
27.6 minutes
70 BPM
Total
No./Wt %
533 /100% 1*
111 /100% 2*
448/100% 2*
174/100% 3*
676*/100% 2*
C-1.5 TEST 5
FEED: 2,000 MIXED
SPEED: 60%
Natural HOPE Product
PVC Product
Clear PET Product
Green PET Product
Opaque HOPE Product
BOTTLES
Nat HOPE
No./Wt %
471/85.68%
1/ 0.09%
PVC
No./Wt %
3/ 0.50%
104/92.47%
4/ 1.87%*
COMPONENT
Clear PET
No./Wt %
4/ 0.81%
2/ 2.14%*
417/92.57%
20/11.23%*
V 0.10%
Green PET
Mo./Wt %
3/ 0.67%
2/ 2.35%*
2/ 0.49%
124/76.51%
10/ 1.14%
DATE:
DURATION:
FEED RATE:
Opaque HOPE
No./Wt %
43/12.34%*
21 3.04%
22/ 6.95%*
13/10.39%*
669/98.66%
10/08/92
28.0 minutes
69 BPM
Total
No./Wt %
524/100% 1*
110/100% 2*
441 /100% 1*
161 /100% 3*
681 /100%
C-1.6 TEST 6
FEED: 2,000 MIXED
SPEED: 60%
Natural HOPE Product
PVC Product
Clear PET Product
Green PET Product
Opaque HOPE Product
BOTTLES
Nat HOPE
No./Wt %
459/84.13%
3/ 0.28%
PVC
No./Wt %
97/86.31%
6/ 1.17%*
3/ 1.42%*
1/ 0.09%*
COMPONENT
Clear PET
No./Wt %
3/ 0.61%
6/ 6.42%*
397/93.13%
26/14.84%*
6/ 0.63%*
Green PET
No./Wt %
1/ 0.22%
1/ 1.18%*
4/ 1.03%*
118/73.99%
15/ 1.72%
DATE:
DURATION:
FEED RATE:
Opaque HOPE
No./Wt %
52/15.04%*
4/ 6.09%*
14/ 4.67%
12/ 9.74%*
654/97.28%
10/08/92
26.9 minutes
70 BPM
Total
No./Wt %
515/100% 1*
108/100% 3*
421 /100% 2*
159/100% 3*
679*/100% 3*
C-1.7 TEST 7
FEED: 2,000 MIXED
SPEED: 60%
BOTTLES
DATE:
DURATION:
FEED RATE:
10/08/92
25.3 minutes
75 BPM
COMPONENT
Natural HOPE Product
PVC. Product
Clear PET Product
Green PET Product
Opaoue HOPE Product
Nat HOPE
No./Wt,%
460/83.53%
M 0.10%
PVC
No./Wt %
M 0.17%
102/78.67%
3/ 0.54%*
4/ 2.00%*
Clear PET
No./Wt %
4/ 0.81%
14/12.99%*
407/88.29%
18/10.85%*
4/ 0.43%*
Green PET
No./Wt %
4/ 0.89%
3/ 3.06%*
8/ 1.91%*
107/70.85%
14/ 1.66%
Opaque HOPE
No./Wt %
51/14.61%*
4/ 5.28%*
30/ 9.26%*
19/16.29%*
639/97.82%
Total
No./Wt %
520/100% 1*
123/100% 3*
448/100% 3*
148/100% 3*
658*/100% 2*
Excessive contamination indicated by *.
Total column excessive contamination notation indicates the number of contaminants (ex. 3*).
71
-------
TABLE C-1. CONTINUED
C-1. 8 TEST 8
FEED: 2,000 MIXED
SPEED: 60%
BOTTLES
Nat HOPE
No./Wt %
Natural HOPE Product
PVC Product
Clear PET Product
Green PET Product
Opaque HOPE Product
471/86.72%
3/ 2.57%*
2/ 0.37%*
3/ 0.28%
No
PVC -
./Wt %
101/79.
71 1.
4/ 1.
85%
20%*
91%*
COMPONENT
Clear PET
No./Wt %
1/ 0.20%
6/ 5.71%*
424/87.79%
14/ 8.06%
5/ 0.52%*
Green PET
No./Wt %
1/ 1.05%*
4/ 0.91%
123/77.75%
13/ 1.49%
DATE:
DURATION:
FEED RATE:
Opaque HOPE
No./Wt %
45/13.08%*
8/10.83%*
33/. 9.72%*
15/12.28%*
659/97.71%
10/08/92
26.5 minutes
73 BPM
Total
No./Wt %
517/100%
119/100%
470/100%
156/100%
680*/100%
1*
4*
3*
2*
2*
C-1. 9 TEST 9
FEED: 2,000 MIXED
SPEED: 60%
Natural HOPE Product
PVC Product
Clear PET Product
Green PET Product
Opaque HOPE Product
BOTTLES
Nat
No.
HOPE
/Wt %
475/86.59%
M 1.02%*
2/ 1.05%*
M 0.10%
No
PVC
./Wt %
95/89.
9/ 1.
5/ 2.
2/ 0.
07%
43%*
42%*
18%*
COMPONENT
Clear PET
No./Wt %
5/ 1.01%
2/ 2.26%*
411/78.55%
30/17.46%*
5/ 0.54%*
Green PET
No./Wt %
4/ 0.
V 1.
6/ 1.
112/71.
18/ 2.
89%
24%*
26%*
62%
14%
DATE:
DURATION:
FEED RATE:
Opaque HOPE
No./Wt %
40/11.51%*
4/ 6.42%*
69/18.76%*
9/ 7.45%*
631/97.04%
10/08/92
26.1 minutes
74 BPM
Total
No./Wt %
524/100%
103/100%
495 /100%
158/100%
65 7*1 100%
1*
4*
3*
4*
3*
C-1. 10 TEST 10
FEED: 2,000 MIXED
SPEED: 60%
Natural HOPE Product
PVC Product
Clear PET Product
Green PET Product
Opaaue HOPE Product
BOTTLES
Nat
No.
HOPE
/Wt %
460/87.65%
2/ 1.10%*
5/ 0.46%
PVC
No./Wt %
99/82.53%
6/ 1.10%*
3/ 1.52%*
M 0.09%
COMPONENT
Clear PET
No./Wt %
5/ 1.06%
71 7.02%*
421/93.00%
4/ 2.43%
2/ 0.21%
Green PET
No./Wt %
2/0.
3/ 3.
V 0.
120/80.
12/ 1.
46%
31%*
24%
23%
35%
DATE:
DURATION:
FEED RATE:
Opaque HOPE
No./Wt %
36/10.83%*
5/ 7.14%*
18/ 5.66%*
17/14.72%*
670/97.89%
10/09/92
26.0 minutes
73 BPM
Total
No./Wt %
503/100%
114/100%
446/100%
146/100%
690/100%
1*
3*
2*
3*
C-1. 11 TEST 11
FEED: 2,000 MIXED
SPEED: 60%
Natural HOPE Product
PVC Product
Clear PET Product
Green PET Product
Opaaue HOPE Product
BOTTLES
Nat
No.
HOPE
/Wt %
470/88.24%
M 0.83%*
1/ 0.44%*
7/ 0.64%
PVC
No./Wt %
1/ 0.
102/78.
4/ 0.
3/ 1.
M 0.
17%
15%
81%*
21%*
08%*
COMPONENT
Clear PET
No./Wt %
3/ 0.62%
10/ 9.22%*
390/95.18%
42/20.44%*
5/ 0.50%*
Green PET
No./Wt %
2/ 0.
125/66.
13/ 1.
54%
83%
44%
DATE:
DURATION:
FEED RATE:
Opaque HOPE
No./Wt %
37/10.96%*
9/11.80%*
10/ 3.47%
16/11.08%*
678/97.33%
10/09/92
25.8 minutes
75 BPM
Total
No./Wt %
511/100%
122/100%
406/100%
187/100%
704*/100%
1*
3*
1*
4*
3*
Excessive contamination indicated by *.
Total column excessive contamination notation indicates the number of contaminants (ex. 3*
72
-------
TABLE C-1. CONTINUED
C-1.12 TEST 12
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
Natural HOPE Product
PVC Product
Clear PET Product
Green PET Product
Opaque HOPE Product
Nat HOPE
No./Wt %
477/88.21%
1/ 0.89%*
M 0.56%
5/ 0.45%
PVC
No./Ut %
M 0.17%
100/81.68%
5/ 0.94%*
6/ 3.11%*
COMPONENT
Clear PET
No./Wt %
4/ 0.82%
77 6.88%*
417/94.68%
17/10.61%*
5/ 0.49%*
Green PET
No./Wt %
DATE:
DURATION:
FEED RATE:
Opaque HOPE
No./Wt %
37/10.80%*
2/ 2.16%* 6/ 8.39%*
2/ 0.50% 12/ 3.88%
125/85.71%
14/ 1.52% 694/97.54%
10/09/92
26.0 minutes
75 BPM
Total
No./Wt %
519/100% 1*
116/100% 4*
436/100% 1*
149/100% 2*
718*7100% 2*
C-1. 13 TEST 13
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
Natural HOPE Product
PVC Product
Clear PET Product
Green PET Product
Opaque HOPE Product
Nat HOPE
No./Wt %
486/93.33%
4/ 0.38%
PVC
No./Wt %
97/76.71%
10/ 1.76%*
4/ 1.82%*
17 0.09%
COMPONENT
Clear PET
No./Wt %
12/11.42%*
421/89.11%
107 5.48%
3/ 0.31%
Green PET
No./Wt %
17 1.05%*
3/ 0.70%
128/77.10%
8/ 0.92%
DATE:
DURATION:
FEED RATE:
Opaque HOPE
No./Wt %
22/ 6.67%*
8/10.83%*
28/ 8.43%*
20/15.60%*
663/98.31%
10/09/92
25.3 minutes
76 BPM
Total
No./Wt %
508/100% 1*
118/100% 3*
462/100% 2*
162/100% 2*
679/100%
C-1. 14 TEST 14
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
DATE:
DURATION:
FEED RATE:
10/09/92
25.3 minutes
76 BPM
COMPONENT
Natural HOPE Product
PVC Product
Clear PET Product
Green PET Product
Opaque HOPE Product
Nat HOPE
No./Wt %
470/91.38%
5/ 0.46%
PVC
No./Ut %
97/83.30%
10/ 1.78%*
5/ 2.44%*
Clear PET
No./Wt %
3/ 0.65%
4/ 4.13%*
432/92.35%
4/ 2.35%
57 0.51%
Green PET
No./Wt %
2/ 2.27%*
3/ 0.70%
127/81.86%
8/ 0.90%
Opaque HOPE
No./Wt %
26/ 7.98%*
7/10.29%*
17/ 5.17%*
16/13.35%*
675/98.13%
Total
No./Wt %
499/100% 1*
110/100% 3*
462/100% 2*
152/100% 2*
693 /100%
C-1. 15 TEST 15
FEED: 2,000 MIXED BOTTLES
SPEED: 60%
DATE:
DURATION:
FEED RATE:
10/09/92
24.4 minutes
79 BPM
COMPONENT
Natural HOPE Product
PVC Product
Clear PET Product
Green PET Product
Opaque HOPE Product
Nat HOPE
No./Wt %
466/91.01%
2/ 2.04%
M 0.19%
5/ 0.44%
PVC
No./Wt %
2/ 0.36%
95/89.24%
8/ 1.43%*
6/ 3.18%*
M 0.08%
Clear PET
No./Wt %
3/ 3.39%*
430/92.60%
117 7.03%
37 0.29%
Green PET
No./Wt %
3/ 3.73%*
5/ 1.18%*
115/80.70%
14/ 1.50%
Opaque HOPE
No./Wt %
287 8.63%*
17 1.61%
157 4.59%
10/ 9.09%*
702/97.68%
Total
No./Wt %
496/100% 1*
104/100% 2*
459/100% 2*
142/100% 2*
725/100%
Excessive contamination indicated by *.
Total column excessive contamination notation indicates the number of contaminants (ex.
3*3.
73
-------
GLOSSARY OF TERMS
Availability - The probability that equipment will be capable of performing its specified function when
called upon at any random point in time. Calculated as the ratio of run time to the sum of run time and
downtime.
Bottle - A single plastic container, also referred to as a container.
Cascade - To sequentially increase the belt speed in a series of conveyors.
Contamination - Bottles improperly removed at a station.
Effective Bottle Feed Rate - The average rate at which a specific type of bottle is fed during a mixed
composition test. Calculated as the total number of bottles of a specific type fed divided by the total run
time for a specific test.
Extended Test - A test series consisting of many replicates at pre-selected conditions.
Fed - Refers to bottles removed from the feed bin by conveyor C2 and either removed by the oversize
station, spilled, or delivered to conveyor C3.
Confidence Interval - The range in which an estimated population statistic is expected to fall with a
specified degree of confidence based on sample statistics. Confidence intervals can be calculated for
statistics such as the population mean and standard deviation. The confidence interval for the mean is
calculated using the Student's t Distribution, and the confidence interval for the standard deviation is
calculated using the Chi-Square Distribution. The 95 percent confidence interval is a range around the
statistic such that 2.5 percent of the area under the distribution curve falls in each "tail" of the distribution.
For example, if the sample mean is 90 and the 95 percent confidence interval is calculated to be the
mean plus or minus 2, one would be 95 percent confident that the population mean would be within the
range 88 to 92.
Confidence Limit - The value below and above the sample statistic defining the limits of the confidence
interval. For example, in the above example, the lower confidence limit is 88 and the upper confidence
limit is 92.
Maintainability - A measure of the ease with which an equipment item or system can be maintained in
proper running condition. Measured by parameters such as the Preventive Maintenance Ratio, the
Corrective Maintenance Ratio, the Maintainability Index, the Mean Time To Repair, and the Mean Time
Between Maintenance Actions.
Mistake - This is a bottle erroneously removed at a station.
Mixed Composition - Feedstock consisting of a mixture of resin types.
74
-------
Overall Bottle Feed Rate - Calculated as the total number of bottles fed divided by the total run time for a
particular test.
Outlier - A test replicate judged to be unrepresentative when compared to the entire set of test replicates.
Percent of Fed - Refers to the number of bottles of a particular type recovered at a particular station as a
percentage of the number of bottles of that type fed by conveyor C2.
Percent of Presented - Refers to the number of bottles of a particular type recovered at a particular
station as a percentage of the number of bottles of that type presented to that station.
Population - The entire group of data, also referred to as the universe.
Presented - Refers to the bottles available for removal at a particular identification/separation station.
RAM Analysis - An evaluation of the reliability, availability, and maintainability of an equipment item or a
system.
Recovery - Refers to bottles properly removed at a station. For example clear PET removed at the clear
PET station is recovered at this station. Any other bottle type removed here is considered a mistake and
results in contamination of the clear PET product.
Reliability - The probability that a system and its components will perform satisfactorily according to its
intended function over the duration of their mission. Measured by three factors: the mean time between
failures, the mean time to repair, and the mean time between maintenance actions. In probability form it
is e (2.71828) raised to minus 1 times the ratio of the desired uninterrupted operating time divided by
the mean time between failures.
Replicate - A distinct test run on a particular feedstock. Multiple replicates comprise a test series. Also
referred to as a test or test replicate.
Sample - A subset of the population.
Single Composition - Feedstock consisting of only one resin type.
Slug - A group of several bottles delivered simultaneously.
Spillage - A bottle that falls or bounces out of the system after being picked up by conveyor C2 such that
it is not available for identification and separation.
Station - The point of removal of each bottle type.
75
if U.S. GOVERNMENT PRINTING OFFICE: 1993750-002 / 80273
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