Document 6B7eqyEbn37YqQ3gQoNb8NZDg
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nloading and storage technique ggBKwnyl chloride monomer
. ? - The system, described here is critical to the safe of thb widely discussed carcinogen.
-.
Ant Muktrji, Catalytic Inc.
m
T - < SaiBanui tests and consequent governmental reg-
residue liquid. This liquid can be transferred by con
.jd*Qpns have rtrahHshsd vinyl chloride monomer (vcm)
necting the compressor's suction to the tank car, and its
" *.a.dangcrirucarcinogen.* Manufacture* ofvcm have discharge to the storage tank. A four-way valve in the
_____ a accordingly modified plant* to protect workers from qwttaet with the chemical
suction and discharge lines effects this changeover without exposing the operator to vcm.
the changeover, one step ha* become critical to the
With the normal compresKr Sow thus revened, re
twerall procow for converting toxic vcm to tafe polyvi- sidual liquid in the tank car vaporizes from the reduc
' *iXny}. chloride (wc)--the loading itep, where vcm from
tion in pressure, while the compressed vapors are con
2p8kiC|us and tank trade* ia loaded into a customer's densed in the storage tank by bubbling them through
tank* far ptucrasing to pvc. Since the polymcri-
the large mass of Squid, which removes the heat of
plants are relatively smaller than vcm plant*, and
compression. In this manner, the tank car is normally
*atdispersed near to their market*, the critical loading evacuated down to the premure required for reloading.
;* efriiyi am maoy-
Depending on the heat transfer into the tank car,
Mpeeovirv'.vapora from an empty vcm storage tank., residual liquid vaporizes within JO to 30 minutes, dur
ffiauwt.hn collected and contained a* they are displaced- ing which, time the pressure will nor be radically re
,,
iy at nemyipply of liquid, became of mingent specifi-
duced. After the liquid has been vaporized, the time for
otipnrat tq permissible.concentrations of veu in- the
evacuating the remaining vapor* may be ralralatnri
^.':^P^.*rmo,Ph<g^-s
with the formula;
v S-"V
''fSdtt further. vcm ia an explotion hazard, cormpaadr"'ng to Cbssil, Group D,' Div. 1, of the National Etectri-
Mm(V/DE)ln(Pt/Pt)
^ cal Manufacture!* jun. code, kxma 7, and variation* in
; __ _ . ambient temperatures at varioua location* complicate ^M^fulxbeuratdooconlaading/loading problem. .
where: M = evaporation time, min. V s tank-car volume, ft.* D -- compressor piston displacement, ft*/min.
exchange
.key- to*" solving them problems consists of a g.. * vapotvUquid-eachange procem, which ha* been incor-
Ipnrsrtnd into' the design of a number of successfully
Pt st tank-car pressure at start of cycle, psia Pt s tank-car pressure at end of cycle, psia * = average volumetric efficiency of compres
sor
jryiiniwgMwir^tiiig' stations (Fig. 1). With this procem,
The economics of the evacuation operation can be
^ ^ tScempressar draws vapor from the plant's storage tank, evaluated according to the value of vcm.
-rV^|5c find feed* the compreaMd vapor into a tank car, foidng
After the tank car has been completely evacuated, the
7-' ~- -j vat from the tank car up through a dip tube and.into compressor i* used to evacuate the disconnected hose,
*&jr'the transfer-piping system.
which only then should betaken off far storage.
- E;., '..Alternately, a slipstream of liquid vcm from the stor-
The storage tank b emptied of vcm for maintenance
;f;;-ago--tank is vaporized by steam to similarly increase by filling it with water as rtiipltrrd vapor* are vented to
fiihbear pressure: The vaporizer generally come* into a monomer gas collecting ryxtein, and then letting in air
Tt'' v . play-ertherwhen the compressor is down for maintc- through the atmospheric vent as the water is drained
naaeo. or when ambient temperatures'are too low into the diked storage area, for runes' to storm sewen.
V~ ` ,-n >.'fbeiow60'FT for the- compressor alone to handle the
'tip. unlo*dipg<^,:'x-
. Unloading system
t-v'Unng the compressor, vcm transfer continues until
The unloading system consist* of transfer piping,
UgX S' &i tlifr-lcvel- in the tank car fall* below the dip pipe, at compressor, vaporizer, storage tanks, *nd instrumenta
/ winch point-the tank car is full of displaced vapors plus
tion for safety and control. Flexible metal hoses w>n"v
<. . "
,,
,
the tank car to the rigid transfer piping. Each transfer
Hkm *f- Mss 13.1ST*, p. S3j July *, 1574. p 28, Sc. 2.1974. p. 23. r I*, Ssyse90,1*74,piu;Sine30.1974,p.42;Feb. !7,1973,p S3, Mar 17, 1973. 7 * -fcS^W- 9. 1973, |d5S. Or*. 13,1973, p 7. J. 3, 1976, p. >4
connection on the tank car contain* an isolation valve and a built-in excess-flow valve to prevent leakage in
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CHEMICAL tMdMUaiM SEFTEMSSa I* 1S77
$11091 55
CBY 1661015
RSV0033762
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VCM untoadhtasysMu*
the event of a raptured hose. Similarly, the rigid piping contain* check valves to prevent backflow front the * storage tank in case of rapture.
veu inventory it measured by meant of a turbine rarer and a flow totalizer in the transfer piping. A filter dpsoeam of the meter protects it from dirt, at well at .extending the online time of the monomer-reactor
' charging filter (tee Fig. 1).
V Design criteria The step! in designing a vctt-unloading system gen
erally take the following sequence: 1. Establish the piping configuration for compressor, vaporiser, storage tank and tank car. 2. Determine the optimum transfer-line rise for the {desired flowrate. 3. Size and select the compressor. 4. Develop the detailed instrumentation. The piping configuration is made in accordance with
the flowscheme (Fig. 1) and a physical layout for the
unloading station. Pressure drops in the transfer lines
mutt include static elevation and line loan between the
compreamr discharge and the tank car, and between the
compressor suction and the storage tank. Also, pressure
drops scroti the turbine meter, and a dirty filter, must
be allowed for.
Since the entire unloading area will be outdoor* and
may be in northern climates, the compressor and va
porizer design must allow for seasonal temperatures
such as 110, 0, and 10 *F, corresponding to monomer
vapor pressures of 35, 43 and 11 psia, respectively.
A common practice is to size die compressor for
spring conditions, relying on the vaporizer to augment
transfer during the winter. In this case, the compressor
will unload during summer at a much faster rate, which
can be calculated by trial and error, assuming a flow
rate and working backward through the compressor-
rizing calculations.
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IK CKSM1CAX CJNORQEWNO fOTlMVmz. IfTT CBY 166101a
RSV0033763
Theritcalculations determine the requiredcompressors |
displacement, as ^function of its volumetric efficiency', ]
thjg^apor molecular weight, vapor density and specific
heat, therdischarge and suction temperatures and pres
sures. the tmleadin- rgt, and the beat lost by the tank
tar to its jur- lundm-is rsee dox, o lC).
i The.vaporizer is --tially a vapor, liquid separator
' with srsteam-heatc ' -.amber Liquid vcm flow to this
vessci is about one -artieth of the liquid transferred
' from the tank. Vaporizer design is based on winter
conditions, the worst c-se for unloading vcm. Operating
pressured* the sum ef. storage tank-pressure and the
pressure losses in tt.e- transfer line.
Liquid entrainment m the vapor can be minimized
by introducing a wue-mssn screen to coalesce the liquid
dreplets, and by prodding sufficient due;(gaging height
above the liquid surface
The required mass
of vcm vapor tc the tank
can be taken'from compressor rv-cu'it'-ns for winter
condition*. Thit figure, along with the liquid and vapor rtmsirira of vcm at operating presnireand temperatures, gives the volumetric vapartiowntetn the tank car, and the liquid flowrate re ` r vasenxer.- The remaining vaporizer design ca*diIarions--dewith steam require ments and heat-transfifr surfaces^-'
Instrumentation
All locally mounted electronic instruments must meet the Class 1, Group D, Div. 1 re <uirements of nema 7. Electronic, intrinsically safe, explosion-proof instru ments are available from most vendors, for on-the-spot calibrating and troubleshooting, if required.
Also, electronic instruments should be capable of withstanding seasonal temperature extremes. Other wise, heater* or coolers m^st oe used. Pneumatic local instruments should be weatherproof and dust-tight
The totalizer. er* with the turbine meter in the transfer line, ditpiavi tne instantaneous vcm
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CSV 1661017
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RSV0033764
Jfn CTKD1UW MONOUtt
and accumulates the actual vex removed on both rttable batch counter and a continuous counter, in ' to be able to display vex unloaded from several cars after a period of time- The batch counter tag is dogged after unloading each tank car, and before unloading the nex* i compute a material balance, a reactor batch ge, and a reaction conversion, the operator must v the total weight of vex unloaded into the storage s. Since the density of unloaded vex varies with tent temperance, a temperature-compensated flow
surement is required. he turbine meter affords an accuracy of d;0.15 to 25% of the instantaneous Sow. For such accuracy, netef vendors must have densir. and viscosity data
for seasonal conditions. Also, the transfer line roust provide straight runs of 15 pipe diameters upstream and 5 pipe diameters downstream of the meter.
The totalizer should have built-in low-flow and high-flow switches. The low-flow gives indication when (1) the filter ahead of the meter is plugged, or (2) the manual valves m the transfer line are blocked, or (3) the compressor is malfunctioning. The high-flow protects the turbine meter from overspeeding due to vapor flow, by stopping the compressor. Vapor flow occurs when
the liquid level in the unloading tank ear drops below the dip pipe. Overspeeding the turbine reduces the life of its bearings and may damage the rotor. Even after the compressor stops, vapor flow will continue until the tank car and storage tank have achieved the same
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pressure, which can introduce significant error in the totalized reading.
This vapor flow can be avoided :?y pi icing an auto matic on-off valve, actuated by a density-difference or pressure switch, at the tank-car end of the transfer line.
Thejevel indication on a storage tank permits sched uling that tank for reloading and production, whether the tank has enough material to charge a reactor batch or whether a tank car's contents can be unloaded into it. Magnetic and capacitance-type level meters provide a reading unaffected by the varying vex density. Read ings that depend on liquid pressure, on the other hand, jvil] vary with ambient temperature.
A high-level switch interlocked with the storage-tank unloading pumps prevents cavitation by maintaining enough liquid head at the pump suction.
In the event of fire, an automatic fine-valve on the storage tank's discharge line isolates the tank. Normally, a fire-safe full-port ball valve with pneumatic actuator
serves tor this purpose. The firr detector can be a bimetallic switch set at 170*F near the fire valve. A relief-valve/rupture-disc combination protects the stor age tank from overpressure due to fire or overfilling. A
redundant relief system on each tank prevents acciden tal shutdown.
A self-actuated excess-flow valve downstream of the fire valve isolates the storage tank in case of line rup ture, or failure of the reactor charge-valve, or an instru ment malfunction in the vcM-reactor charging system. Fire and excess-flow valves are dose-coupled to the storage tank and interlocked with the storage-tank un loading pump to prevent evacuation of pump suction lines with these valves dosed, and thereby prevent over heating the pump.
For multiple storage-tanks using several unloading compressors and unloading pumps, the installation re quires multiposition selector-switches to facilitate auto matic interlocking of the selected tank instruments with the pump and compressor in use. Instrumentation for tnc compressor indudes gages to display discharge pres sure, and a rclief-valve/rupture-disk combination to protect positive-displacement compressors. It is not
good practice to pipe the discharge of this valve to the compressor suction, because of possible overheating due to continuous recirculation and recompression.
A liquid trap on the compressor suction side 310914
CHEMICAL ENCINEHUNG SEFTEMSOt 12 If?'
59
CBY 1661019
RSV0033766
VtNYL CHLOPUP* MOHOME*
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mizes chances for slugs of liquid to reach the compres sor. A high4evel switch ui the liquid trap is interlocked, to shut down the compressor, and the trap is steamtraced and insulated to reduce the accumulation of liquid. Instruments for the compressor and liquid traps generally come as parr of the compressor package. Pres sure and level controls on the vaporizer aid the unload ing operation by nuantaining heat and material bal ances, respectively. Pressure is maintained through the heat input to the vaporizer, and the level is held con stant by-liquid vcm flow.
Since the vaporizer operating pressure is higher than the storage-tank pressure, the storage-tank unloading pumps must supply a slip-stream of chloride to the vaporizer. Possible cavitation damage to the level-con-' trol valve can be eliminated by means of a valve with a high'recovery coefficient or anticavitation trim.
A relief-valve/rupture-disk combination protects the vaporizer from overpressure due to fire, or steam-valve or level-valve failure. The steam valve is interlocked with the high-flow cutoff switch of the unloading system protecting the turbine meter.
Safety
Area monitors are located at breathing level in the work areas to detect vcm emissions. Since vinyl chloride vapor is heavier than air, it has a tendency to move downward, so detectors for combustible gases should be located at an elevation of 2% ft, near the sources of po&ible vcm vapor leaks.
vcm concentration, measured in ppm by a chromato graph, is displayed, and an alarm sounds when this concentration exceeds 75% of maximum permissible.
vcm concentration as a percentage of vcm's lower ex plosive limit is also displayed, monitored and alarmed--aa measured by a remote combustibles ana lyzer. Because of the distance between the polymeriza tion-reactor control room and the unloading area, it is usually convenient to group controls and instruments for vcm unloading on a nearby water- and dust-tight control panel. The control room operator needs only the critical data for overall coordination--such as storage tank level; and the status of the unloading compressor, the fire and excess-flow valves, and the unloading pump. A remote pushbutton can be interlocked with all the fire valves on storage tanks, in order to dose those valves in an emergency.
Relief valves protect the transfer piping from thermal expansion wherever liquid can be blocked between valves. The blinded vent on the storage tank is equipped with a flame arrester to prevent flash-back into the tank.
The author Aw Mukiiji u * accuor loatruiscat "fM*1 with Caudytjc, Inc., t500 Market Street, Philadelphia, h. 19102, where he hat amred u lead inatnimenc ai|iwg for a vanatr of project*. He hsi had pnor drain aao application atpenenee with an marramcat manufacturer in India. He holdk u MS degree from Dreed Uniwarty and i Bi degree from die Jcuhao Zneucute of Technology, Bombay, m chemical engineering
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CHEMICAL ENCINZZJUHC SEFTEMSES Ji 1*T7
CBY 1661020
RSV0033767
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rtmT--fug iiniilTf) mi ii'iiiimnU iii i iiillnii iilinf i*i thins maiii** ilii i On* ii mjc*2]r th* creator* team analyzing leefexueca by thin-layer-- be protwfted beat dim In
ceav `hhao*'
w:
r intensfcianatural resistance assn alter-, chromatography can screen ?40 "proge- resemble-those used to immunuo'iip^
btjr* to ehnu>a. pMtiddec. Alio, nut-'.. ay" par day--which is easier and quicker mala. Experiments with watermelon*
- ml productchemistsare becoming moewC. than- waiting to bob which plants the muskmalons, and cucumbers showed, fo*_ . awareed the oppoitunitiaefor research worm* eat and which ooaa they don't. example, that innoculation ofjust one leaf -.y
the field and Mte-nncnci)entietttflQp^HOur(nidentandmf ofthesmetumand ofs young plantwith a pathogenic fungus ~
niquee ar* making:roclr research moe*." bkyntheis.of the cotton terpenoids, is-- would produce lesions onihat leaf and the' feasible. Paahapeiaiefcftrifriilaafc.isth^ff aliasing nsto predictwhat can andean* leaf would die. However, Kui layerthe
'facrtlutitheFbodAIJnigAdjniiMtiatiaaiS^nof be accomplished to increase-host limited infection stimulated a protective--
i expected toi*sueregulationsto eneuial . plant resistance by genetic manipula- - response thet spreed through the growing
that:change*madein-plants to devetopw tion.'fStipenoviccomments,
plant The effect lasted four to five weeim.
raaiatiam else eun*r rnncritoU hazards^ - Ofcourse, plant*mint resistdjaeasee aa. A "booster" innoculation, three weeks
lielha 1--lihiWIiilliitfiiniiflnnnaae awiu weUaa-inaecta,According.toDn Noel:T.- after the first extended the syetemicak Kaeo and: Dk Baradt Braaggart piantr protection through the fruiting period, '
Twamh,wilkbarequbadtp obtainthen pathologieteal tiw UniversityofCalifq..,. Experiment*.to, find the-"chemical'
niatJttvnddairatJaaahTS epeciaaofhighar signaL" that turns onthe immune system
compi^intbiheregulationa.-.'-' x
plsnta. are now known-to. mafcaruphyto - pi* now: underway, Kui note* If found,
. JSattaa.understanding, of thrmacbee* alexiia,^ or chemical, compounds- that: he (ays, it could eliminatethe need to use
niMHifcmfctviQuatth* dmkd
help ward off infection. These are low., living organisms to- impart protection?-
. tiwieailerlmei'ilen wittaanplifrlhepiidaT- molecular:weight substance* .euchres seeds could be treated with the chemical,
f.'jfi `' hbnwwddwwnnffauwnniiliy'iigdarwdiiig toaDrcAnthoueager-. terpenoids,-iseflaveooid*^ and- phenolsj* thereby' immunizing-the germinating
fct. C.. Waieea * phytocbamiss afcUSEAfed, tW aplantnormally produces onlyafUe- asirtTififi . "
> Q.
WSinHagHaial TTaaaaujli Canraa, AU: it has..beam, infected, byt pathogens*- * ,,>
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h'asrinffWtiirrhu raaaaitb larkofcrtiaen Whatharsadtnwhatxt*!i**ptieprst-.
*>' "W* - tj
ktintisdlpeliw aeywtha*- forcedtpianta ducaa these aatihiaticcotupoimrinrtiteai, CtaMolrsairangementSL^-
ghsdWaisSea^i
mineuitajeeistxaeecc:mecaptahility tot dlseawii.Ifsrtiok readydeairthlag Kaonr
dufabadbicyci reactions
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sepaptdriiyicebkeedpbnt*tha*nraduew>_- odI-.TrHaatejrrw*,t*Sv
largeqttfHtitlaatdphytoaltriiiai ijtss^*
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tobequrtetaskcRatbescthepwiifctofind. ady'rip*,'twSrmiefaos -
patfiagnm tha<bJth#sJaa%)phytosla*iiii` ____ prndfinHrti* ifi/ay-^g;
** ipWhsllwaiHiaasaiiaitiirsaagansiifHfiiSP -i vi, i.nH -iwr genarskhathte-ectinpia>tho-eMbiaaS'<illr-
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FasedamphailiaiiiassaSthsUStlAlalaiii Thm hpdiwrawplaidmwitfrsepaaid-to>~ sthnuletHmc.by * singiw eiiaitQSrt Theyb prcpeaaxfoc mumplarnntba hsaia oftfaair
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.lhagabue wadi with anyhisn* thrt itmrtnral char
cottonmagrplayo canefoundinthe cellwslleofmany fungf.
armajaeToiminim
to-the? playa gsnsratrdarin plantrseiatanc*to-,
^ cotton budwonn, and certain,poly infeedoff by fimgh-^They note that* glu-
phenols protect com'against BarwormsT' can-containing; fractJon'ertrscted' fronr
Til lie an fei niigsel Mini ....... hrewertyeaeSjhownally nonpathogan)
imparting, natural^eaistance are more isjurt aseffective in athrmladTig soybeans,
selectiveto theirtazidtjr andare atzst< ^ toeynthenssphytoalaxm as is the ducan
gically locatedin the plant to affecttarge*- front.pethogaaicfnngakvsrietiae Valent.
iniertSwfWer anas of the efbctivimaai dry and~Albcisherov also suggest that appli-
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Bicycha enthusiasts may be happy to learn ihat they have aiUee-)n the molecUar realm, Dr. Howard E. Zimmerman ot the- Univarslty of Wlaconsln, Medaon, told the ayrrpoeium an organic,
pbotpchemiahy, apcneored by hie Di vision-ot Organic Chemistry, of a claaeof H^iHndijced- reactions he- calls
"bicycle reactions.'. Aa he describes on* such reacdoit.'The- C-6 of * 2--
nuertirida*" Wsiaa wnphasim* homma,^__Phytaakcdns alone cant entirely ae W^reeiatance^ aad"siieceptsbility^afW*>,:BPiiiUiiMrLliiieeee neietenremplants,say eladve. term* not. abeoiutaa. And' b*-.; DrtJneepfeKugandDr. Frank-L, Caruaoi ;points, out, ag* end babiw of that plant*. ofthe department of plar^petfology atj
meifiytaneblcycio(3tt.0)fisat - 3 - one slKhere along the pi system of a fulvene-
moiety to the exocycllc pi bond, thus. gMnge aplro(2.4)hept* a.a diene.Therearrangement can beenvisaged ms lie.
envimiiiuaiitalfiectog*and insectfeeding-: the UnivsrsiftfofKentucky; texingtoo. i
beharior alaoplay importantroleeisthw . They note-that much "protected!' tiaaue-
totalsrhem*-- 1-'
`-'1 -: - in. plants contains no: phytoaiexina^'
veMng a carhanokl cation (tor man*-, pie, C-6) bicycling on the tutvene pL system uemg Its sp4hybrid orbitals^*
- AtUSDA'a NatianalCotton Palhak>gys> Rathe* it appears that at leest-. tbre#-"
Laboratory, CoDsg* Station, Tom. Drtv mecbeniamsmustbe coordinatedto pro-
Robert D. Stipanovic, working witti-Drw^. videtheprotective leeponaetoinfaction..
Alois A. Befi and- Texas AdM
Qa* ieetacts penetration of "pathogens'
DenialHtO'Brien;hasfound that cottas*: ihto-. the; plant- Another cause* th*
leaves and flower buds contain- several*? pathogens' to- chimp, inhibiting, theirr
- natiSrak-- "helioeides-"--terpenoid*-aft1.' spread through tissues. A third mecha^
dahyinatbatarwtonctohelintiusapBcieeisI? msm hinders the growth or rmiltiplirstifia
, mdndinf the cottoa bollworm-and thee ' ofthe pathogens. Also. Knfc note*, aggiu*
tobecrxr hudworm. At least: 10 rotated?.- tin* in the plut may react wititenzymaac
^^coi^pBnndsareinvolsedStipaiioviczH*se^-. and toxins produced, by ths pathogens,-
jTTi^fiatua^ a singlB leafia neededto revs^.-. thus abating the symptoms of the dis-`-
'wheels" and Its exo and ando ivristlt-- uants aa 'handlebars.'" Atthouf- It la notdearwherethpacialaanaanectie&they seemto turn In only one directions
Zimmerman and hla colleague Timothy P. Cutler have shown that except In special circumstances*-the carbenokt bicycle wWl move only oountenjlockwae-
around-the ring. They describe three: mor*.examples-of the reectkxi In a paper aubnrittad to the Axanal of the AmericanChemteaf Society.
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.^ ... 1 CBY 1661021
Sept'IZ 187TC4Q4
RSV0033768