American Mineralogist, Volume 65,pages 1053-1056, 1980
A simplerapid-quenchdesignfor cold-sealpressurevessels
Genv K. JAcoBsAND DERRTLLM. Kennrcr
Departmentof Geosciences,
ThePennsylvaniaState University
University Park, PennsylvaniaI 6802
Abstract
A simple rapid-quenchdesign,utilizing conventionalcold-sealpressurevessels,operates
by flushing the capsulechamber with cold water injected through an axial capillary tube.
Comparedto a conventionalair quench,improved quench ratesare gained without the disadvantagesassociatedwith other rapid-quenchmethods(e.g.water-bathimmersionor waterjacketed tilt mechanisms).The need for a rapid quench is illustrated by quenchreactionsin
experimentswith wollastonite-bearingequilibria in H2O-CO, fluids. Upon air quenching,
wollastonitereactswith CO, to form calcite and (presumably)silica in solution. Quenching
experimentsinvolving wollastoniteand HrO-CO, fluids indicate that back-reactionduring
cooling is minimized through use of the new rapid-quenchdesign.
Introduction
to minimize temperature gradients (Boettcher and
Kerrick, l97l). Temperatures(12"C) were measured
with an internal, inconel-sheathed,chromel-alumel
thermocouplewhich, along with capillary A (Fig. l),
extendsthrough the hollow filler rod to the position
of the capsules.Both the thermocoupleand capillary
A were silver-solderedto the nipple at the top of the
T-junction. Valve A is used to isolate the pressure
vesselfrom the main pressureline aftbr final pressure
adjustments are completed. Using water ?s a medium, pressureswere generatedwith an air-driven
hydraulic pump (Haskel # osxuw-903). Pressures
(120 bars) were monitored with a bourdon-tube
gauge for each vessel,catbrated against a factorycalibrated standardgauge.
At the end of an experiment,pressurein the main
line (Fig. l) is equalizedto that in the vessel.Valve A
is then openedto connectthe vesselto the main pressure line. The vesselis then removed from the furnace,placedin a streamof compressedair, and valve
B is immediately opened,allowing the hot water in
the vesselto exit through the T-junction, capillary B,
and bleed line. Cool water, pumped in through capillary A as the hydrautc pump cyclesto maintain constant pressure,flows over (and quenches)the. capsules (see inset in Fig. l). A large-volum€ water
Rapidquenchmechanism
reservoirbetweeneach vesseland the main pressure
Figure I is a schematicdiagram illustrating the line should help reduce momentary pressuredrops
rapid-quenchdesignusedin this study. In our exper- which occur between each cycle of the hydraulic
iments, the pressurevesselwas oriented horizontally pump. When the vesselis cool, pumping is stopped
0003-004x/80/09
l 0-I 053$02.00
1053
Interpretation of hydrothermalexperimentscan be
complicated by the precipitation of undesirable
phasesduring quenching of conventional cold-seal
pressurevessels.For example,calcite readily forms
during compressedair quenchesin experimentsinvolving wollastonite equilibria in HrO-CO, fluids
(Kerrick and Ghent, 1980;Johannes,personalcommunication; Shmulovich, 1977;Ziegenbein and Johannes,1974).Although rapid quenchingof the pressurevesselthrough immersioninto a water bath may
alleviate this problem, repeated quenching by this
method can shortenvessellife and lead to explosive
failure. Use of water-jacketedrapid-quench vessels
can be quite successftrlin reducingquenchproblems,
provided precautions pointed out by Ludington
(1978) and Rudert et al. (1976\ are observed.The
present paper describesa new rapid-quench design
that utilizes a conventional cold-sealvessel(Tuttle,
1949)through which cool water is injected into the
capsulechambervia an axial capillary tube; this procedureresultsin a rapid temperaturedrop in the immediate vicinity of the capsules.This new design is
simple and requireslittle modification of a cold-seal
hydrothermal laboratory.
t054
JACOBS AND KERRICK: COLD.SEAL PR,ESSUNE VESSELS
lnternol
Thermocouple
'Leods
- MoinPressure
Lrneto Pump
C o p i l l o rAy
V o l v eA
..Closure
Assembly
Cold-Seol
Pressure,'
Vessel_,-,
T
,,r_
I
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.-l
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Qumch reactions
The rapid-quenchmechanismwas used to reduce
quench reactions in experimentsdealing with wollastonite in HrO-CO, fluids. As noted in the introduction, several authors have observed that wollastonite reacts with CO, during the quench to form
calcite and SiOr. X-ray analysis(Guinier camera)of
some experimental charges where wollastonite reacted with CO, during the quench yielded patterns of
wollastonite and calcite, but not quartz. This phenomenon, which was also observed in experiments
by Shmulovich(1977),implies that quartz is not precipitating along with calcite; thus, silica remains in
solution, and/ot is present as an amorphousphase.
SEM photographs of wollastonite from such experimental charges support this hypothesis. Abundant
calcite rhombohedrons can be seenon the wollastonite grains; however, quartz is noticeably absent. One
of the authors (D. M. Kerrick) has frequently encountered
this phenomenon in thin sections of wolThermocouple
Well
lastonite-bearing metacarbonaterocks.
Agro-Pdrocapsules were loaded with equal
Fig. l. Schematic diagram of the rapid-quench design.
Enlarged inset shows details of hollow filler rod, internal
thermocouple, and capillary A, illustrating flow of cool water
(arrows) around the capsules.
and the pressureallowed to drop by closing valve A
and letting the water flow out of the bleed line.
Experimental results
o Compressed
Air Quench
o "Roprd"
Quench
400
T("C)
300
Quenchrates
Quench rates from conventional compressed air
quenches are compared to those utilizing the rapidquench mechanismin Figure 2. The rapid-quench
apparatus yields significantly larger temperature
drops over the first 40 secondsofthe quench.In fact,
temperaturesrecorded with the rapid-quench mechanism averaged150'C below thoseof the compressed
air quench for the time span of 20-40 seconds. A
temperaturedrop of 400o (from 600o to 200'C) occurs in about two thirds of the time with the rapidquench design as it does with a compressed air
quench. These results indicate that problems with
quench reactionsmay be alleviated (or minimized)
by utilizing the rapid-quench apparatus.
20
40
60
80
100
',120 140
160
Time (secs)
Fig. 2. Temperature-time plot comparing conventional
comprcssed-air quench to that using the rapid-qucnch design.
Each symbol representsan averageof3 values. Initial temperature
was 600oC at a total pressureof 2.0 kbar.
JACOBS AND KERRICK: COLD.SEAL PRESSURE VESSELS
Initiol moles CO2 x 106
45
90
135
180
o
a
(o
-8
a
-rz
f
N
o
o -re
o
c)
o -20
E
4 -ro
a Compressed
Arr Quench
o " R o p i dQ" u e n c h
04
Initiol
a
a
a
06
08
X"o"
Fig. 3. Change in moles of CO2 (final moles - initial
resulting from the quench reaction: wollastonite * COz +
* SiO2. Runs were quenched from the wollastonite + fluid
700"C and a total pressure of 1.0 kbar. A value of zero
ordinate indicates no back-reaction.
moles)
calcite
field at
on the
amounts of -325 mesh wollastonite (for a chemical
analysis of this specimen see Kerrick and Ghent,
1980)and silver oxalate + HrO for the generationof
various initial values of Xco, (Hunt and Kerrick,
1977;Slaughteret al.,1975). For each capsul€,the
ratio of wollastonite to fluid was approximately 8:2
(by weight). To eliminate any reaction betweenthe
wollastoniteand CO, which may have occurredduring the run-up, the capsuleswere first subjectedto 914 day runs at 700"C and I kbar-conditions well
within the wollastonite stability field (Greenwood,
1967).Somevesselswere then quenchedwith a conventional compressedair stream,while others were
cooled with the rapid-quench apparatus.The final
compositionof the fluid phasewasdeterminedby the
weight-lossmethod of Johannes(1969).Initial and final amountsof CO, in the capsulesshould be identical if no quench reaction occurred.However,if wollastonite reactedwith CO, during the quench, a net
loss of CO, should be observed.Becausepressure,
X"o,, arlrdsurface area of wollastonite were kept constant in setsof experimentsutilizing the two quenching techniques,the change in moles of CO, should
provide a good comparisonof the degreeof back-reaction of the two different quench methods for each
set of runs.
Figure 3 showsthe resultsfrom the quenchingexperiments.At all initial X.o. values,someback-reaction occurred,evidencedby the net lossof CO, for all
data points. However, the rapid-quench technique
yielded smaller CO, lossesthan the compressedair
quench.This is especiallyevident at high initial Xco,
values.For theseCOr-rich compositions,the quench
path entersthe calcite + qaaftz stability field at relatively high temperatures,where enhancedreaction
kinetics causegreater lossesof COr. Note, however,
that for both quench methodsthe maximum loss of
CO, occurs at initial Xco,: 0.6 rather than initial
X.o, : 0.8. Apparently, quenching at initial Xco,:
0.6 representsthe optimal combination of the rateenhancingeffectsof HrO and elevatedtemperature.
Back-reactionis very limited at initial Xco,:0.2 and
0.4 (seeFig. 3), which implies that even though the
fluids are very water-rich,the temperaturesat which
the quench path penetratesthe calcite * quartz field
are too low for extensive back-reaction to occur.
Thus, for this reaction, quench products are most
likely to form in CO,-rich fluids during the initial
temperature drop of the quench, where the rapidquench apparatus was shown to be most effective
(seeFig. 2).
Discussion
Our rapid-quenchdeviceyields fasterquenchrates
thair conventional compressed air methods. Although quenchrateswith this deviceare not as rapid
as water-immersion methods or water-jacketedtilt
vessels,this new design does offer some advantages.
It avoids the large temperature gradients which can
be associatedwith somewater-jacketedrapid-quench
vessels(Ludington, 1978;Rudert et al.,1976).In addition" with this new designit is possibleto carefully
check sampletemperaturesthrough use of an i-nternal thermocouple;the design of tilt-mechanismvesselsprecludesthe useof internal thermocouples.Our
rapid-quench design should provide a safe alternative to water-immersionmethodsunder normal operatimgP-T conditions for cold-seal vessels,because
compared to water immersion, the relatively small
mass of injected water yields smaller overall shortterm strain on the vessel.No failures have occurred
in approxinately two dozenruns with the new design
at pressuresto 2 kbar and temperaturesto 700'C.
Actual quench rates with other pressuremedia such
as Ar or CO, have not been measured;however,improved quench rates are anticipated with the rapidquenchdesigncomparedto compressedair quenches
with thesepressuremedia.
As evidencedby experimentson the back-reaction
of wollastonite during quenching, the new design
does not eliminate all quench problems, but it does
reducethem to a more acceptablelevel.
1056
JACOBS AND KERRICK: COLD-SEAL PRESSURT VESSELS
Acknowledgments
We thank I-Ming Chou and D. H. Eggler for their careful review of this paper. This work represents part of G. K. Jacobs'
Ph.D. research and was supported in part by NSF grants EAR 7684199 and EAR 79-082,U (D. M. Kerrick) and an Owens-Corning
Fiberglas Graduate Fellowship (G. K. Jacobs).
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Manuscript received, February 15, 1980;
acceptedfor publication, May 9, 1980.