1992 National Waste Processing Conference 22

7/23/2019 1992 National Waste Processing Conference 22

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DEVELOPMENT OF AN AUTOMATED COLOR

SORTING SYSTE FOR RECYCLABLE GLASS

CONTAINERS

M R LEWS A T A EWELLDepartment of Mecanica and Industria Engineering

University of Illinois at UrbanaampaignUrbana Illinois

ABSTRA

An automated optica coor sorting system for recyclable gass containers as been developed as a fulscaleprototype and tested at a materias recovery facilityTe system employs ve vertica cutes tat sort woleclear containers out of a mixedcolor stream, and isterefore a separation aid for tree color sorting. Testsindicate a 70% success rate at 125 ton/r/cute wilete number of cutes used can be matced to processing needs Te success rate is % after bot automated and manual sorting ave been completed Eaccute as a control circuit wit tree critical variabeparameters tat can be adjusted to increase te automated sorter's success rate. A computer simulation and

optimiation routine ave been written to nd te optima combination of te tree circuit settings An economic analysis compares te automated/manual system to an allmanual system and nds a payback periodof less tan 2 years for a recycing center serving apopuation of 5.

NOMENCLATURE

b brown or amber gass

Institute for Local Sef-Reance, Washngton D

97

C capita cost of automated botte sorting system ($)

c clear or int glass

C overal capacity of te automated/manualsystem (tonsour)

cas ow ($) number of cutes required

D annual depreciation of automated bottesorting system ($)

fpm feet per minutef single cute feed rate (bottles/second)g green or emerald glass ination rate

lcf least coor fraction

LL lower limit of te window comparator of tecontro circuit VLS labor savings ($)

MR material recovery facilityn = number of years (years)

NV = net present vaue ($)

PC = processing cost of te automated/manualsystem ($/ton)

overall processing rate of te automated/manual system (bottles/second)

V present vaue ($)W

puse widt (msec)

interest rate


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S saage aue of auoaed boe soringsyse ($)

SUC = suess rae of he auoaed sorer ax rae

x annual ax paid on pros ($)L iing ii of he R oponen of he

onrol irui ()

UL upper lii of he window oparaor of heonro irui ()

INTRODucnON

Reyling akes sense iied naural resouresare saed energy onsupion is redued and airwaer and land poluion are u when reyling subsiues for one-ie use. Aerians produe approxiaey 35 lb of rash per day and wih gass opris

ing oer 8% of our wase srea (wih oer haf of habeing onainer gass) he iporane of glass reylingis ear

Gass onainers are oleed hrough arious progras oe of he ore oon oleion prograsinlude urbside drop o buy bak oerial andinsiuional Boles are deliered o a proessing faiiy oonly referred o as a MR (aeria reoeryfaiiy) where olor soring onainan reoaoue reduion and arkeing an ake pae. A asaoriy of glass onainers are one of hree oors in(lear) eerald (green) or aber rown) In order o

ee he arkeing requireens of he anufaurerswho l he gass onainers olor soring us ouro high oleranes lear glass has a ore sringenpuriy oerane han green or brown. ear boesanno be produed fro brown or green glass

Manua olor soring of glass is haardous sow andexpensie diaing a need for auoaion Reogniion of his proble was he genesis of his auoaedlear/olor glass onainer soring researh and deeopen proe [1] The auoaed sorer is inseredupsrea fro a anua sorer o separae ou os

of he lear boles fro he ixed oor inpu glassonainer srea The auoaed syse is herefore aseparaion aid o he anua sorer In he auoaedsyse onainers are eeaed and hen desendhrough an aignen sage as hey ener he op of aerial sensing hue ree falling hrough a bea ofligh he boles eae a haraerisi rae on an opial sensor. This inforaion passes ino an adusableonrol irui where a yes/no deision is ade dierif lear or do no dier if nonlear. As a ear boleexis he boo of he hue a diersion gae auaed

by wo soenoids diers he boe o he lear inpu.

98

A nonlear bole passes by he nonauaed diersiongae o he oor oupu. The wo oupu sreas henproeed ia horiona and parale oneyors o heanual sorer

An iniia laboraory prooype was deelopedhrough seeral ieraions of experienaion. hen areasonabe leel of odene was gained a fulsale

produion prooype was designed onsrued esedand odied Trial runs of he fulsae syse wereopleed and opared o an alanua syse odeerine eonoi feasibiiy

Many researhers in boh indusry and aadeiahae aeped o deelop an auoaed reyabegass onainer oor soring syse and hese proesan be diided by a nuber of haraerisis. Aepsin he 1960s and 1970s o soe his probe fousedon ule oor soring as opposed o whoe onainersoring 2] Many reen aeps inuding he eor

deaied here folow he whoe onainer approah [3]A a oon sense eel soring one large piee ofgass appears siper han soring seera sall piees;howeer ule soring proes aep o apiaieon preexising ining and agriulure soring ehnoogy A seond aspe is he sensing approah used.igh reeane was aeped in he eary uebased syses A aoriy of reen and urren proes are based on ligh ransiane inluding hesube of his paper ideo iaging is a hird approahbeing inesigaed in soe urren proes A hirdaspe is he eel of auoaion desired Al syses

inesigaed aep o opleey displae he needfor a anua sorer whih diers fro he auhorsapproah of parial auoaion By leaing a anuasorer in he syse an oeral suess rae approahing % an be realied whie he anuasorers proessing rae will be greay inreased wihhe addiion of he auoaed sorer.

Three faors deerine he feasibiliy of a boeoor soring syse suess rae; feed rae; and os (boh iniia apial inesen and operaingos) The suess rae is a onsrain deerined by

he buyer of he olor sored ulle (i.e a glass fuaeoperaor) Puriy eels of 99% and greaer are ofendeanded for in ule whie green and aber areonly sighy ess sringen If a soring syse does noee his onsrain hen i fails The feed rae is aonsrain deerined by he glass onainer proessorwhih is ofen a MR. The feed rae us be fasenough o adequaely proess he olues of glass hahe MR wans o handle in a gien period of ieos he hird faor enais he iniia apial inesen of he soring syse purhaser and he oninu

ous operaing os of ha syse. Power requireens


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aligmethopper

opticalsesor

diversiogate

color

output

o _ lightsource

cear

output

FIG. SCHEMATC OF THE LABORATORYPROTOTYPE

of ost systes inestigated are inia so the ajor

ontinuous ost to be onsidered is abor

APPARATUS

Laboratory Prototype

In order to test the initia hyothesis that is gassontainers an be otiay dierentiated by oor andthen ehaniay sorted a rst generation aboratoryrototye (ig 1) was onstruted Gass ontainersenter the syste ia a downward soing trough andenter a ertia sensing hute with an 8in square oening oated at the to entrane of the hute is a 15inong sringoaded and hinged aignent hoer

199

A red high intensity ight eitting diode (ED)uinous intensity 5 iiandes (d) funtions as the ight soure roiding a narrow fousedsteady bea of ight whie drawing ery itte urrent[axiu ontinuous forward urrent = 50 iiA

eres and axiu forward otage at 20 = 25 ] and haing a ery ong ife (aroxiatey10 hr)

Initiay arious hotoresistors were tested as sensors nay setting on a adiu sude hoto ewith a surfae area of 045 square entieters ()Due to a sow tie resonse the hotoe was reaedwith a hotootai sensor wo were exained aexibe aorhous siion soar e and a oyrystaine rigid siion soar e he seond sensor wasseeted oer the rst for its greater otage oututand is suerior oer the hotoresistor in two riaryregards a arger surfae area (8 ) and aquiker tie resonse he sensor used has a axiuotage rating of 055 V and axiu urrent ratingof 03 A

Prodtio Prototype

he fusae rodution rototye syste is oosed of e arae ertia sensing hutes and hasbeen tested at a MR the ounity Reying enter (R) haaign Iinois A sheati of the

autoated/anua syste is shown in ig 2 he oera diensions of the syste are height 11 (335 )width 4 ft 7 in (140 ) deth 2 ft 8 in (081 )Bottes trae u the 45 deg inined inut oneyor at60 f (030 /s) he ontainers fa onto the troughra and boune and side through the e troughs(ig 3) he bottes then ass through the aignenthoers whih sere three uroses ertia aignent of the bottes entering of the bottes so thatthey ass through the ight bea and seed redution of the bottes to faiitate a onger sensor reading

he bottes then ass through the ight beas and theight transittane is sensed and assed on to the ontro iruits A high intensity red ED with a uinousintensity of 2 d is used as the ight soure and asiion soar e (2 by 4 ) ats as the sensor as the aboratory rototye

igure 4 disays the inforation ow through theiruit Initiay the signa fro the soar e ust beaied fro the iiot ee to a 10 V ee hisis aoished by an instruentation aier withan adjustabe gain whih aso ats to ter out noisehe aied signa feeds direty into a window oarator whih used two o as ne oares thesigna to the uer iit UL and the other heks


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v

FG SCHEATC OF THE AUTOATED SORTER NNE WTH A ANUA SORTER

against the lower iit LL he liits are adjustabewith indiidua ariabe resistors. he signal then owsto a transistor ating as a swith he outut of thewindow oarator is therefore either high or owhis on/o signal feeds into an R (resistor/aaitor)oonent. hen the inoing signal stes u froero to the high aue, the R begins to buid exonentialy. hen the signal dros bak to ero, the Routut deays exonentially toward ero he oututof the R oonent ows into a single oaratorand is heked against an adjustable tiing liit TLIf the liit is exeeded, the usually high outut of theoarator stes down to ero unti the iit is nolonger exeeded. his falling edge is needed to triggerthe next oonent, a 556 tier hi. hen triggered,the 556 sends out a ositie ulse of adjustabe width(. his ulse ows into an nn Darlington transistor array. hen the ulse for a lear signa ows intothe base of the transistor, a + 2 use of equaduration oing direty fro the ower suy owsto a solid state reay. he relay is otialy isolated witha tria hen triggered, the relay loses its inteal

swith on an A line. his 5 A use ows to two

2

Ue tughs

/I"

wedg

FG3 SCHEATC OF THE AGNENT, SENSNGAND DVERSON SECTONS

heayduty solenoids that eah hae a -in. trae. he

soenoids then at to swing out a diersion gate therebydierting a lear ontainer.

o aid in data oletion and in loating syste robles, D ounters and indiator Es were addedto the rodution rototye ontrol box. Eah hutehas two ounters, a ounter reset button, and twoEs. ne ounter sus the nuber of diersion signals rodued by the iruit. his nuber ideallyshould ath the nuber of lear bottles in a bath ofontainers roessed. A green ED tus on with eahdiersion. he other ounter sus the tota nuber of

ontainers that ass through its orresonding hute.A red ED ikers a nuber of ties, with eah disrution of the ight bea on the sensor yieding a bottle in the hute indiation.

Experime Resls

In an eort to deterine the feasibility of the autoated/anual sorting syste, tests were erfored toasertain the suess rate at arious feed rates using thefulsale rototye at R. Exerients were o

leted using one, three, four and e hutes. In addition


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ltge s f fie clcul8age 1.0

uerlH

er l

im "m

o

UL

3aU

9e 1

(V)

vo 3

e 1

(V)

vo

' 1.5 .

:

I

r

0

0 -

0 5e

(V) 00:

voI

e 1(V

15 _ -v 10a

9e

(V) 0-

20 40 60 80 00i (

FG 4 CRCT BOCK AGRAM ANCORRESPONNG COMPONENT OTPT GRAPHS

to varying the feed rate, the olor mix of the inputstream was also varied

igure 5 shows the atual suess rates of many ofthe trials as a funtion of the feed rate The feed rate isa rough estimate The input onveyor delivers one leatof bottles per seond, thus the manually ontrolled

number of bottles per leat was divided by the numberof hutes operating in a given test to arrive at thefeed rate ottle/seond/hute) The results show adereasing auray trend when the feed rate inreases.This is to be expeted as the sensor reeives less information per bottle at a faster feed rate onlear resultswere always more suessful than lear results meaning that the iruits were set onservatively so as notto divert olor bottles into the lear stream The satterin the data is due to the relatively small sample size ()of some trials, and the better performane of the 5 hute

test may be linked to its unreorded input olor mixAdditionally, various iruit settings UL, LL, TL,W) were used throughout the tests

201

08

06success

e

0.4

02

00

00

00

0

05 10 15fe ae (bnle/sce)

o 5 cte es (n15 o 189, va x) 4 ce es (-0 o 62 va )

3 ce es (lll 7, 60:2020 x) 1 ce es (198 602020 mi) 1 cte de pn (n201 60:2020)

1 cte LCD ue (1 2020 mix)

20

FG5 SCCESS RATE AS A FNCTON OF FEERATE FOR A OF THE HGH VOME GASS TESTS

10

08u

06

0

02

o o

FG6 SCCESS RATES FROM A SNGE CHTE

TRA AT ONE BOTE PER SECON FOR THEACTA OTPT, THE COMPTER MOE AN THE

C CONTERS

igure 6 displays results from one of a series of dataaquisition tests performed on individual hutes Dataaquisition hardware was attahed to the output of theinstrumentation amplier on the ontrol iruit andit reorded the ampied sensor output for individual

bottles Roughly 2 bottles with a 60% lear 20%green 20% brown mix were used in eah test and eahhute was tested twie In addition to the sensor traes


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the atual output ount was reorded as were the Dtotas. The digitized sensor traes were then used asinput data for a omputer oded mathematial modelof the ontrol iruit. The output of the omputer simulation is the suess rate at the supplied iruit settings.igure 6 ompares the three versions of the results ofone of the tests for hute 3 The omputer simulation

is aso used as the foundation of a searh routine thatattempts to nd the optimal ombination of iruitsettings UL LL TL The general onlusion of alarger number of searh trias was that the iruit wasfairly impervious to minor hanges in the settings, mostlikely due to the variable nature of the botte streamand bottle onguration in free fal past the sensor.

The atua values of the suess rates of the multiplehute trias are ower than antiipated This expetationis based on the previous single hute trials that employed a more ontrolled delivery of ontainers. In ig.

6, 119 ear, 39 green and 4 bwn bottles were passedthrough the hute at approximately one bottle per leat(one bottle/seond/hute) An atual overal suessrate of 65% was realized (50% lear, 87% olor). Thisis signiantly greater than the 45% suess rates at onebottle/se realized from the multihute trial shown inig. 5

Three immediate reasons for this disrepany arise.The rst is the possibiity of dramatially dierent sample sets of ontainers. or exampe, if one set had beenstored outside on a dry gravel lot, then a oating of

dust oud exist over most of the bottles in that setThis oating of extea dirt woud ower the amountof light that ould pass through al three olors ofglass neessitating dierent iruit settings The seondpossibiity revolves around the iruit settings themselves The 3 hute data in ig. 5 were aquired withUL 76 V LL 3 V and TL 21 V The hute3 data in ig 6 used UL 70 V LL 37 and TL 23 V The seond set of data has a ower windowof similar height, and a onger timing limit. The thirdfator involves bottle interation. In the mutihute

tests, three bottles were on eah eat and passedthrough the trough setion together. Possiby two oreven three of the ontainers oud have traveled downone hute, resulting in a doubled or tripled (respetively) feed rate Even the three bottes reahed individua hutes, their interations with eah other omingo of the onveyor and entering the hutes ould inrease or derease the speed of a given bottle If thebottle is delayed, then a botte from the next leat (ifnot delayed itsel will be less than one seond behindthe rst one And, as ig. 5 shows, dereasing the

spaing between bottes dereases the suess rate.

202

ome potential room for improvement is indiatedin ig 6 As the graph shows, a strong orrelation existsbetween the omputer model and the atua results forthe nonlear ontainers The model predits a highersuess rate for lear, however, than the atual resutsshow. The D ounters ear suess rate is sightyess than the model predition, and the ounters are an

aurate representation of the atua attempted diversions. This eads to the onlusion that a signiantnumber of lear bottles are deteted as ear, but themehania diversion system does not ivert al of theseontainers. The entral problem here lies in timing. fthe timing problems an be addressed suessfuly, thenthe total suess rate oud rise to the evel preditedby the omputer simulation (65% at one botte/se fora single hute).

Regarding the systems optimal overal suess rateas a funtion of feed rate, 56% suess at 05 botte/

seond/hute appears to be the best resut from thehigh volume, multiple hute tests If the negative eetsof bottle interation an be redued then the suessrate an potentialy rise to the singe hute level of65% at 1 botte/se (approximately 125 tonhr or 113metri ton/h). If eah bottle identied as lear wasatualy diverted, then the auray oud rise to theD ounter leve of 70% at bottle/se. This wouldrequire improvements in the timing of the diversionsetion inaly, if the real system t the preditions ofthe mathematial model, then the suess rate would

rise to 74% at bottle/se. This oud be aomplishedby using eetroni omponents with tighter toleraneswhih would provide more aurately known values tobe used in the mode mprovements in the modelwoud lower the predited suess rate by bringing themode more in ine with the atual system.

These results show a lower suess rate than previously run laboratory prototype tests, where singeontainers were dropped down the single hute anddiversions were reorded iruit settings were hosenby experimentation and intuition Twentysix bottles

were dropped individually, 20 times eah (haf bottomrst, haf top rst), totaling 520 sampes. The suessrates for lear, oor and tota were 76%, 91% and83% respetively, for a 58% ear to 42% olor ratio.

In another aboratory prototype test, bottes wereontinualy fed through the system. The overall suessrate was 87% for a 6% ear to 39% olor inputratio. eed rates of 058185 bottles/se were observedtranslating to a range of 993359 bhr for one hute(45630 kg/h/hute). uess rates varied from433% to 872% for al of the tests ompleted on both

systems.


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ANAYSIS

Addtona nformaton regardng the nomng gassstream oor omposton and the manua sortng proessng rate was oeted. ureys of the arous oeton programs of the ommunty Reyng entershowed that the oor rato ares aross oeton programs neghborhoods seasons and other fators Theresdenta tras ared between 50% and 67% earwth the remander spt between green and brownommera oads ared between 10% and 25% earAn aerage botte mass was determned to be 07 b(318 g)

n an amanua system the manua sorter addressesa snge nput stream of mxed oor ontaners andsorts out the two esser fratons nto ther ndduaoutputs n ths way the argest fraton s negateysorted mnmzng the abor requred. Manua proessng speed was determned to be a funton of eprmary arabes fraton of botte stream requrng a poste sort; rato of the two esser oorfratons to eah other; stream densty; eort ofthe manua sorter; and apabty of the manuasorter. Assumng an oera fraton sorted of 2060%and a sustanabe work eort for a apabe sorter a 1botte/se sortng rate s assumed for the anayss Thstransated to an amanua system proessng rate of25 bottes/se (assumng a 60/20/20 ear/green/brown rato) beause a majorty of the stream (60%)s negatey sorted Ths s equaent to 3.15 tonshrAssumng a popuaton of 5 n a ommuntysered by a snge MR wth a reoery rate of 25%approxmatey 25 tons (22680 t) of ontaner gassw be reyed annuay. Assumng a abor rate of$1Ohr to support a manua sorter an annua aborost of $19841 woud resut ($3 17/ton)

orkng as a separaton ad the automated ear/oor sortng system s desgned to redue the personhours requred to proess a gen apaty of gass ontaners Ths s aompshed by redung the numberof physa separatons that the manua sorter mustperform whe mantanng a suenty hgh feed ratefor the manua sorter. The automated sorter spts thenomng three oor stream nto two fratons oneprmary ear the other prmary green and brownThe manua sorter then sorts brown (or green) fromthe greenbrown stream and must aso sort nonderted ear bottes nto the ear stream and norretyderted nonear bottes from the ear oneyor tothe green or brown output Despte the suess rate ofthe automated sorter the nshed produt of the totasortng proess w be three bns of oor sorted uet

203

approahng 1% oor purty due to the manuasorter addressng the output of the automated sorter.

The two prmary osts assoated wth the automated/manua system are apta equpment osts andabor osts ost of an automated sorter has not been

determned exaty but a range of $1$30 hasbeen estmated for a 2 to 20hute system. Ths ntaapta ost must be oset by abor sangs reazedoer the usefu fe of the automated system for t to beeonomay feasbe

The automated system s of moduar desgn aowngthe user to spefy the number of erta sensng/derson hutes to math the proessng needs of the genfaty auatng the number of hutes requred depends on the manua sortng speed the empra suess rate of the automated sorter and

the hute feed rate (). n equaton form

02 090 (1) {round u J (2)[1 - ]

where s east oor fraton (20% for ether greenor brown n the urrent exampe) The exampe s ontnued wth the foowng performane estmates of theautomated sorter

manua sorting rat: 10 bott/sc:10 bottl/sc/chut

0210 090 70%10 bott/sc

[1 070 070020] 10 bott/sc/chut

23 chuts ' 3 chuts rqurdne Eq (2) does not equa an nteger number ofhutes a sower feed rate must be auated wth therounded up nteger number of hutes

(3)[1 -

10 bott/sc [ 0.70 070020]3 chuts 076 bott/sc/chut


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This llows icrese i the success rte of the utomted sorter to be clcuted usig Eq () The ewfeed d success rtes re the used i ccultig theutomtedmul system's processig rte d cpcity

SUC

02076 bottl/sc/chut

090()

75%The umber of chutes required by Eq (2) is ot

fuctio of the overll cpcity of MR but rtherclibrtes the processig d success rtes of the utomted sorter to mtch the mul sorter's speed Ithis wy the mul sorter is ot forced to std idleor stop the processig ie to ctch up

The overl cpcity of the utomtedmul system is fuctio of the umber of chutes feed rte

success rte mul sortig rte d gss iput stremcolor compositio

(5)mass ) ton )36 sc)

calms=(ams)

botte 20lb 1 hr(6)

otiuig the exmple:

0.76 bott/sc3 chuts

23 botts/scC 23 botts)07 b) ton )36 sc)sc bott 2 lb I hr

286 ton/hrA commuity of 5 persos with 25% recov

ery rte is ow exmied to cotiue the curret exmple. or typicl curbside lod of gss (60% cler20% gree 20% brow) the mul sorter works toe botte per secod i cojuctio with the three

chute utomted sorter with iput speed of 076bottlesecchute At verge mss of 07 bottethe utomtedmul system sorts 286 tohr Attht rte 2185 persohours (pproximtely 7 hrweek) would be eeded to process the ul moutof glss recovered (6250 tos) At the bor rte of $10hr this would result i ul lbor cost of $21825d processig cost of $1.75to.

glass rcovrdabor hours ----C

(7)

20

Equtio (7) is i u terms e shift for siglemul sorter totls 2080 hryer d two shifts totl160 hryer If lbor hours exceeds 2080 hr thedditiol sorters secod shi or both c be ddedhutes my be dded i clusters of the umber clcuted Eq. (2) (oe cluster per ech dditio mulsorter) This wil icrese the ctul umber of chutes

so tht the tot lbor vue pproches but does otexceed 2080 or 160 hryer Equtio (8) clcultesthe umber of custers of chutes depedig upo if oeor two shis re used I Eq. (9) d (0) "chutesrefers to the rouded up iteger umber of chuteseeded s clculted usig Eq (2)

numbr of custrs abor hours round uof chuts 2080 or 460

actual numbr of chuts

chutsnumbr ofcustrs of chutsnumbr of manua sortrs

actua numbr of chuts round uchuts

abor cost abor hoursJlabor rat

(8)

(9)

(10)

()

Equtios (5) d (6) which re depedet o the umber of chutes used must be reclcuted before theprocessig cost of the utomtedmul system

) c be clculted

actua actual numbr of chutsactua C actua mass ))36 sc)bott 2 lb hr

labor rat

PC

aactu C

(12)

(13)

(1)

6250 ton/yaraborhourslm= 285 rsonhr/yar286 tonhr

285 rsonhr/yarnumbr of custrs of chuts 2080 rsonhr/yar 2 custrs

actua numbr of chuts

32

6 chuts


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6 chutesnumber of manua sorters = = 2 manual sorters3 chutes($10)

abor cost=

2,183 person-hr=

$21,830actual = 6 chutes0.76 bottle/s/chute

= 45 bottes/secbottles (0 7 b)( 1 ton ) 3sec)actua Cams=4.5- bottle 20 lb 1hr

ton=573. hr

$10hr = = $1.75/tona 573 tonr

This example yields a 0% negative savings in laborhours when using the automated sorter, or a $1984 lossin labor costs.

An annual cash ow (C, over the life of the machine, must be compared to the capital cost of theautomated system This comparison incorporates the

labor cost savings (LS), annual straight-line depreciation of the automated system D the capital cost ofthe machine (, its salvage value at the end of its usefullife (, the tax rate of the rm buying the sorter the ination rate the interest rate ) and the numberof years of the life of the system (n. Power costs areassumed negligible for the automated sorter, as themain power draw will be from the infeed conveyor,which is also required in the all-manual case The overall present value (V) benets of purchasing the systemless its costs is the net present value of the machine(NV) An NV greater than or equal to zero indicatesa nancially attractive project

= ( of system's Fbenets ( of system's costs

[1 1 + 1 + )" = F 1 + ) _11 + /

=

(15)

(6)

(17)

205

D = - (18)

x = D) (19)

F = D) x + D = - D) 1- ) + D = x (20)

[( S]NPV= LS- (1 - t) +1 + [ 1 + )"

]_

_

1 + )11 + /

(21)

The amount of tax calculated in Eq. (18) holds to beaccurate even if the labor savings (L is negative because it is assumed that the MR will add this loss inwith all of its other projects, and the corporate tax ratewill be applied at that time

ollowing through with the ongoing example, assuming C $2, , S = $5, = 34%, = 4%, = 0%, n = 5 years and LS $397, the NV on theproject is $6619, indicating a poor investment. If,however, the color ratio in a community was 50/25/

25 (clear/greenrown), then the NV would be $2402with a 134 year payback period (Table )

Table shows the results of the economic analysisfor community sizes of ,, 5,, 1 million and5 million people for four dierent clear/greenbrownratios. The NV is calculated based on a 5-year lifeof the automated system A positive NV indicatesa nancially benecial project, while a negative valuereveals a disadvantageous project The payback periodis the number of years required to realize a retu on theinitial investment (I indicates an innite payback

period) All of the other assumptions stated immediately above were used in calculating Table 1 (ie., C =$2 , S = $5, = 34%, 4%, 10%,recovery rate = 25%, labor rate = $1Ohr, and manualsorting rate = 10 bottle/sec), except that the cost ofthe system is estimated at $4 for the 15 to 20chutesize It is assumed that nonsorting time of a manualsorter can be lled with other unrelated MR activities.

A shorter payback period is realized when the colormix approaches equilibrium (i.e., one-third each) Thisis due to the reduced level of the negatively sortedfraction in the manual sorting system comparison, thatis, the automated sorter displaces the greatest amountof labor in this case Also, the larger the population of


10/11

TABE ECONOMIC COMPARISON O NCREASNG POPUATONS OR DERENT CEAR/GREEN/BROWNRATOS OR A SUCCESS RATE O 70% AT A BEGINNNG EED RATE O 10 BOTTE/sec/CHUTE

no of labor system paybackglass collected population no o manua perso capacity perod

c g b persos chutes sorters hours/yr tos/hr NPV years6 1 1 100,000 360 20 20 100,000 350 25 25 100,000 320 40 40 100,000 2

6 1 1 500000 360 20 20 500000 650 25 25 500,000 620 40 40 500,000 4

6 1 1 ,000000 360 20 20 1,000,000 650 25 25 1,000,000 620 40 40 1,000,000 4

6 1 1 5000,000 1560 20 20 5,000,000 1850 25 25 5,000000 1820 40 40 5,000000 14

an ara rvd by a MR with an automatd ortingytm th hortr th payback prod. n hit oabor (2080 hr/yar) could b ud in th two mallr

z communt whl two hi (460 hr/yar)would b ndd or th two largr citi. Ao notworthy i th act that th gratr th utilizaton o thautomatd ytm th hortr th payback priod.

h bt opportunity or improvng th conomco th ytm i to incra t ucc rat throughimprovd matria handing abl 2 how th rultor th am paramtr a ab xcpt or an improvmnt in th ucc rat o th automatd ytm.h prviou xamp aumd a ucc rat o 70%at a d rat o 0 bottl/c/chut whi ab 2aum a ucc rat o 80% at th am d rat.

CONCUSIONS

ytm cot d rat and ucc rat ar th thrcritica actor in valuating a ga containr colororting ytm At a cot o approximatly $2 or a chut ytm plu abor a d rat o .25 tonhr/chut and a % ucc rat th automatd/manual ytm ha potntial. A numbr o phycalmprovmnt o th ulcal prototyp incudng

bott algnmnt pacng and timing ar pannd to b

1111

222

1222

566

206

413 3.02 -$3381 IF43 286 $2,8

IF41 265 $34 88455 21 -$513 2.50

206 302 $12632 IF2183 5.3 -$669 IF2356 5.3 $2402 3428 434 $1,08 .0

4134 302 -$2419 IF4365 5.3 $1210 IF412 53 $58 0.65554 434 $4,483 082

20668 15.2 $118,13 IF21825 .18 -$5800 IF23562 5.92 $32203 030280 52 $25264 038

incorporatd nto a dmontraton unit that wl bdignd a part o a compt ga procing ytm(a oppod to th rtrot approach ud or th pro

duction prototyp) h improvmnt wil incrath ucc rat o th automatd ortr thrby ncraing th d rat o th ytm rducng th laborhour rquird and rducng th payback priod hytm i rcommndd or an intrmdat procngaciity oppod to a gla manuacturng pant Aquality contraint r th cullt ortng approach appar to b aibl. ncrad handlng ncrabottl brakag thu uggting that coor ortng occur a co to th gnrator (.. th conumr) apoib

ACKNOWLEDGEMENTS

h author thank and acknowldg th olowngh linoi Dpartmnt o Enrgy and atural Rourc provdd undng or thi proct through twogrant h ommunity Rcycling ntr hampaignllino uppd al o th tt containr th tt acity and xprt advc on gla contanr rcyclng hDpartmnt o Mchanca and ndutrial Engnrngo th Univrity o lnoi at Urbanahampagn pro

vidd upport. A numbr o ndvidual hav atd


11/11

TABE 2 ECONOMC COMPARISON OF NCREASNG POPUATONS FOR DFFERENT CEAR/GREEN/BROWNRATIOS FOR A SUCCESS RATE OF 80% AT A BEGNNNG FEED RATE OF 0 BOTE/SECOND/CHUTE

no o abor syste aybakgass olleted oulation no o anual per aaity eriod

g b persons) hutes sorters hr/r t/hr NPV ear6 1 1 100,000 360 20 20 100,000 350 25 25 100,000 320 40 40 100,000 2

6 1 1 500,000 360 20 20 500,000 350 25 25 500,000 320 40 40 500,000 4

6 1 1 ,000,000 360 20 20 1,000,000 3

50 25 25 1,000,000 320 40 40 1,000,000 4

6 1 1 5,000,000 1260 20 20 5,000,000 1550 25 25 5,000,000 1520 40 40 5000,000 14

on ths proect ncudng . Apotheker R. O. oweDr. R. Abde-Messh and a number of undergradu

ate engneerng students

REFERENCES

Lews M R Reac and Deveopment of an AutomatedCea/Coo Gass Contane Sotng System fo te Recycng Po

111

1112

1

2

455

207

331 38 $1,068 I35' 350 $43 439 315 $1,08 10516 242 $1,153 216

1653 38 -$1,068 I186 350 $4,483 0821984 315 $12,810 032259 485 $10,034 041

330 38 -$1,068 I351 350 $10,034 041

3968 315 $26,68 016559 485 $21,136 020

16534 15.12 $2,491 I185 1.50 $53,019 01919841 155 $136,284 0082594 1696 $108529 010

cess" M.S Tess Ubana Inos; Unvesty of Inos at UbanaCampagn August 99

[2] Samtu H R Gass Recycng and Reuse" Insttute foEnvonmenta Studes Unvesty of WsconsnMadson Mac974 pp. 5153.

[3] Gtzofe KH Constucton of an Expementa Unt fote Mecanca Coou Sotng of Non-Cused Recyced ContaneGass" Httentecnsce Veengung de Deutscen GasndusteeV (HVG) FanktM FRG) Glastech Ber. , 99 pp. 95

Documents

1992 National Waste Processing Conference 22