I
J O H N W. PAYNE, CARL W. STREED, and ERIC
R. KENT
Research and Development Laboratory, Socony Mobil Oil Co., Inc., Paulsboro, N. J.
The Shaker Bomb A New Laboratory Tool for Sfudying Thermal Processes
bA
significant contribution in the field of high temperature-high pressure liquidvapor reactions by providing a decidedly novel method for rapid initiation and quenching of such reactions in a batch system S m C i . a EQUIPMENT was necessary for conducting thermal studies under carefully controlled temperature-time-pressure conditions in these laboratories. A shaker bomb of unique design was developed to obtain experimental data on such operations as visbreaking, thermal cracking, and coking much more quickly and at less expense than is possible with conventional pilot plants. The shaker bomb is designed to study thermal processes at temperatures generally above 800' F. and at pressures up to 2000 to 3000 pounds. Reaction times are measured and controlled in terms of seconds. Very rapid heating is achieved
by using induction heating, and rapid cooling by using a water spray. StuRing boxes are avoided and violent agitation of the bomb contents is obtained by mounting the bomb on the top of the piston of a motor-driven single-cylinder gasoline engine. The same kind of process information is obtained from shaker bomb experiments as from a large scale pilot plant. In addition to economies in time and cost, the shaker bomb allows a process to be studied over a much Wider range of severities than is otherwise possible, and on much smaller samples of charge. The shaker bomb should be of general value wherever the limitations of conventional stirred batch-reactors (leakage around stirrer shaft, slow response to heating and cooling, and difficulty of obtaining extremely vigorous agitation) are a drawback in studying a high temperature, high pressure reaction. For example, the wide degree of agitation possible should aid in the study of high temperature, high pressure multiphase reactions (such as those using solid catalysts or involving gas-liquid contact) where diffusion rates may limit the rate
THERMOCOUPLE
WATER
LEADS
TO H I G H SPEED TEMPERATURE RECORDER
SPRAY
GAS H O L D E R
EXIBLE
E L E C T R I C MOTOR
VARIABLE SPEED DRIVE
MODIFIED E N G I N E
20 -2000 STROKES /MIN
Shaker bomb unit
TUBING
of chemical reaction. Multiphase reactions and pure thermal reactionse.g., thermal cracking of butane-have not been studied. This article describes the design and operation of a shaker bomb unit and gives some illustrations of the information that can be obtained with it. 8
T h e Shaker Bomb
I
This is the general arrangement of the shaker bomb unit. The essential feature is a small interchangeable metal bomb that can be heated and cooled very rapidly while its contents are being vigorously agitated. Temperature and pressure are measured continuously throughout the reaction period. The bomb, containing the test charge, is mounted on the piston of a modified single-cylinder engine. The engine is driven by an electric motor through a variable-speed drive. The rapid reciprocating motion of the bomb provides agitation and rapid heat transfer to the contents, and avoids the use of a powerdriven stirrer. Agitation may be varied from mild to extremely violent by changing the engine speed. The bomb is fastened to the piston with a sturdy, detachable pin-mounting, so that it reciprocates up and down without sideways motion; yet, it can be readily removed from the unit and replaced with another bomb at the experiment's end. A stationary, rigidly-mounted induction coil surrounds the reciprocating bomb and provides the very high heat input required to heat the bomb and its contents from room temperature to the thermal conversion range of 800' to 1050' F. The combination of ,an uninsulated bomb with induction heating gives very rapid and flexible control over the thermal cycle. At the desired instant, the induction coil is turned off and the reaction is quenched by spraying the bomb with cold water from spray rings mounted near the top and bottom of the induction coil. A high speed VOL. 50, NO. 1
JANUARY 1958
47
[ II[&
DEPRESSWRING TUBE
,
THERMOCOUPLE WELL
ATTACHING PISTON
Reactor bomb design electronic recorder keeps a continuous, simultaneous record of the temperature and pressure within the bomb during the entire cycle of heating, reacting, and cooling. After depressuring by releasing the product gas to a gas holder, the bomb is removed from the unit, sealed, and taken to a laboratory where the liquid products are quantitatively recovered and analyzed. Another charged bomb is then attached to the unit and the next experiment begun. The time required for one complete thermal experiment averages from 30 to 60 minutes. Description of Shaker Bomb Unit
This laboratory has two shaker bomb setups, one for bombs of 300-ml. volume, the other for bombs of 1500-ml. volume. As both setups are very similar in layout and operation, only the 1500-ml. unit is described. Reactor Bombs. The reactor bomb consists of the reaction chamber, the pin adapter for attaching the bomb to the shaker engine piston, and the head adapter to permit temperature and pressure measurements and product removal. Bombs having 4-inch outside diameters with internal volumes of 1500 ml. are used for reaction chambers. They are designed to have minimum possible heat c?pacity consistent with the strength necessary for high temperature, high pressure operation. Minimum metal weight aids greatly in rapid heating and cooling of the bomb and its contents. T h e bomb is fastened to the engine piston by a pin adapter which screws onto a threaded pin mounted on the piston face.
48
The average life of a bomb is 40 to 50 experiments. The bombs usually develop fine cracks in the metal-evidently caused by the repeated sudden heating and sudden quenching of the metal. Shaking Mechanism. The bombs are shaken by attaching them to the piston of a gasoline engine driven by an electric motor. The engine was adapted to this use by replacing the standard cylinder head with a flat plate having an opening for the bomb-mounting pin. The standard piston was replaced with a heavy steel piston, with a thick top to which the connecting pin is attached. The engine is driven by an electric motor through a variable-speed drive equipped with electric positioning motors so that engine speed can be changed from the control board as desired. Any speed ranging from 20 to 2000 r.p.m. can be obtained by presetting with a control button mounted on the control board. (An electric speed indicator is mounted on the control board.) This speed range provides agitations ranging from a mild swirling to violent turbulence. The turbulence achieved by shaking the bomb at various engine speeds was studied by high speed motion pictures with transparent plastic replicas of the metal bombs. The plastic bombs were filled with varying volumes of liquids in which were suspended colored particles having densities close to that of the liquid. Pressure Tubing and Thermocouple Leads. As reactor bombs reciprocate with movements of 4l/2 inches at speeds up to 2000 r.p.m., special connections were developed for pressure tubing and thermocouple. The pressure connection is a length of small bore tubing bent in a way that it has a one-turn coil on either end of the shaker bomb unit. One end of the tubing is attached to the bomb head, and the other end to a stationary post about 16 inches away. With this design, a single loop of tubing can be used for a number of experi-
INDUSTRIAL AND ENGINEERING CHEMISTRY
ments without breaking or without leaking at the end fittings. This technique is satisfactory for work u p to 2000 pounds per square inch gage and for bomb temperatures up to 1000° P. When loop failures occur, they are usually clean breaks adjacent to the fitting on the bomb head adapter. The thermocouple leads from the connector on the bomb head to the recorder are laid against the pressure tubing loop and held in place by a piece of plastic tubing slipped over both pressure tubing and thermocouple leads. Induction Heating. A commercial induction furnace coil used to heat the reciprocating bombs is in the form of a helix wound from closely-spaced spirals of copper tubing. Water is passed through this coil to keep it from overheating. The coil is stationary, surrounding the reciprocating bomb and so placed that the center of the coil is located at about the midpoint of the bomb travel. Coils ordinarily used to heat 1500-ml., 4-inch outside diameter bombs are about 7 inches long by 5lI2 inches inside diameter. A clearance of 1/2 to "4 inch is required between the bomb wall and the inner edge of the coil to prevent arcing from coil to bomb. Quench Cooling. Spray rings are used to spray the hot bomb with cold water to quench the thermal reaction. There are two of these rings, one mounted near the top and the other near the bottom of the induction coil. When an experiment has been completed, quench water is sprayed on the bomb. The bomb and its contents cool very rapidly. The quench water is then shut off and the bomb is ready for depressuring and removal from the unit. An automatic interlocked system shuts off the induction heating the instant quench water is applied. Instruments. Figure 1 shows the panel board and part of the protecthe housing of the shaker bomb unit. On
T H E SHAKER BOMB this panel board are mounted (left to right) a temperature indicator, a high speed combination temperature and pressure recorder, a heat input timer, two length-of-run timers, a watt-meter, and a speed indicator. Adjacent to the panel board and mounted on the outside of the housing (Figure 1, left) are the valves and pressure gages of the unit. The temperature indicator isused tofollow the initial heating process to 600' F.; when that temperature is reached, the high speed temperature-pressure recorder acts to make a permanent record of the experiment on a strip chart. Heat is supplied continuously to the bomb during the heating portion of an experiment; when the desired temperature level has been reached, heat is supplied intermittently to maintain this temperature. In experiments of short duration this is done manually; for long runs the on-off heat input timer is used. One timer measures the total time of an experiment, while the second measures the time at the desired temperature level. The problem of measuring with a thermocouple the correct temperature within a metal bomb mechanically reciprocating in a high frequency electric field was overcome by the use of resistance-capacitance damping in the measuring circuit. The measurements were checked with water-saturated steam in the bomb at pressures up to about 3000 pounds per square inch and temperatures up to 695' F. Housing. For safety, the shaker bomb, together with the shaking mechanism, is surrounded by steel housing. The housing has an exhaust blower to vent any gas which may escape by a leak developing during an experiment. A 20- X 20-inch, 2-inch thick glass window provided in the housing near the operating controls allows theoperator to watch the bomb during operation. The bomb, induction coil, and loop are visible through this window in Figure 1, Only one bomb has failed by rupture in conducting over 3000 individual experiments. This occurred in an experimental study of maximum possible heating rates of the bomb. A bomb charged with oil was being heated at the unusually high rate of about 2500' F. per minute. Delay in pressing the quench button on the control board allowed the bomb wall to reach 1325' F. and the pressure inside the bomb to reach 2400 pounds per square inch, both values being well above the safety limits. The bomb failed by plastic tearing along one side; there was no fragmentation. The hot hydrocarbon vapors ignited on contact with the air and the combustion products were removed by the exhaust fan. There was no damage to any equipment other than the bomb. In a few bombs plastic swelling was
observed in some experiments involving high temperatures where there were high yields of coke from the decomposition of the test oil. I n these cases the coke probably formed a deposit on the inner wall of the bomb and interfered with the transfer of heat from the wall to the oil. The bomb-wall temperature was then considerably higher than the temperature indicated by the thermocouple immersed in the oil; so that, unrecognized by the operator, the metal temperature exceeded design limits. None of these bombs ruptured. Operation
I n carrying out experiments on thermal processing of an oil, the bomb is charged with an accurately weighed amount of the test oil. Because the final pressure in the bomb depends directly upon the amount of oil introduced initially, and because this final pressure must be controlled within safety limits, care is taken to limit the volume of test charge to 25 or 35y0 of the bomb volume, taken at 60' F. After the bomb has been mounted on the shaker and before the experiment is begun, the assembly is pressure-tested with an inert gas to a higher pressure than expected during the experiment. The rate at which the charge is heated to reaction temperature ranges from 3' to 12' F. per second. A rate much lower than 3' F. per second defeats the basic purpose of getting to the reaction temperature quickly, while a rate higher than 12' F. per second leads to an undesirably high temperature differential between the bomb wall and the control thermocouple in the center of the bomb. In special cases, however, heating rates as high as 30' to 40' F. per second have been used. When the desired reaction temperature has been reached, the bomb is held a t the temperature for the specified time. The duration of a run at full temperature and pressure is between 30 and 1500 seconds. Then, when the quench water is applied, the bomb temperature drops at rates as high as 20' F. per second (1200' F. per minute). Some experimental time-temperature patterns in Figure 2 illustrate the ordinary use of the shaker bomb equipment. Because the bombs respond very rapidly to heating and cooling, fairly complex time-temperature operating sequences may be accomplished. These patterns (Figure 2) however, are simple, involving heating, constant temperature, and cooling periods. The constant-temperature traces show how well the temperature may be controlled during the formal reaction period. Some reaction may take place during the heating and cooling periods,
and an allowance for these "end effects" is necessary in some studies. Arrows on the curves show the point a t which quench water was applied. Two traces were obtained with the 1500ml. bomb unit, and the third with the 300-ml. unit. The large bombs may show a lag of about 10 seconds between the instant quench water is applied and the time when the thermocouple begins to record cooling at a high rate. This lag is not important, because it is easily compensated by applying the quench water 10 seconds early, but it does illustrate the differences in temperature that may exist between metal wall and the thermocouple during heating and cooling. The time lag on quenching is much less with smaller bombs (Figure 2) where the weight of metal is less and the ratio of inside bomb wall area to volume of the oil is greater. After the bomb has been cooled, the shaking mechanism and the quench water are shut off and the gas in the bomb is vented to a gas holder. The bomb is then sealed and taken from the shaker unit to a laboratory where the liquid products are measured and analyzed. Control Over Reaction Variables
Temperature a n d Time. From the discussion of Figure 2, the shaker bomb gives direct and very flexible control over temperature and time. The timetemperature pattern used in an experime?t is recorded continuously by the high-speed electronic recorder. Time is measured in seconds. I n the study of thermal conversion of petroleum, the shaker bomb gives precise knowledge of the time-temperature pattern in contrast to pilot plant experiments where the time-temperature pattern cannot be measured directly but can only be roughly estimated. Pressure. I n a typical experiment, the pressure increases throughout the heating and constant temperature period and decreases during quenching. The maximum pressure reached is governed by the volume per cent of the bomb occupied by the initial cold charge oil, the pressure of any gas added to the cold bomb, the boiling range of the charge oil, the reaction temperature, and the extent of conversion to vaporized products. Pressure can be regulated at any constant level throughout the cycle, or can be varied along a predetermined time pattern. This was not done because the effect of pressure on the reactions usually studied is not great enough to warrant the added experimental complexity. In reactions most often studied in the shaker bomb (visbreaking and thermal VOL. 50, NO. 1
JANUARY 1958
49
cracking), pressure has only a small direct influence on the products. I n coking, pressure influences the end boiling point, and, to a limited extent, the boiling curve of the liquid product. I n all three cases, wide variations in pressure do not, in general, produce changes comparable to those observed with moderate changes in temprrature or residence time. However, processing severity in the furnace of a commercial unit is affected by pressure-primarily the result of the change in residence time brought about by the change in specific volume of the vapor-liquid mixture of reactants. illustrative Uses of Shaker
000 O F
700 -
600 -
t0
INDUSTRIAL AND ENGINEERING CHEMISTRY
l
t
60
120
TIME IN SECONDS
Bomb
Petroleum refineries often ask the laboratories for information as to the effect of processing variables on thermal conversions-especially, in the yield of products and their quality. The process variables are the charge stock, temperature, and residence time. Usually, the information is wanted over a range of temperatures and residence times and for several variations in charge stock composition. This information is valuable because the thermal conversion process is only one link in a number of interrelated processes that make u p the overall refining scheme. As there are always a number of alternate arrangements within the over-all scheme, the more information the refiner has concerning each processing step, such as the thermal one, the better he is equipped to select the best arrangement. Some practical information obtained with the shaker bomb is described briefly: Thermal Cracking. Figure 3 shows the product distributions obtained when a sample of a heavy petroleum fraction was thermally cracked in the shaker bomb over a range of severities at two reaction temperatures. This particular study was made to determine whether it would be profitable to include this stock in the charge to an operating thermal unit. The product yields are plotted in Figure 3 against the reaction time at the two temperatures, 845' and 900' F. To be of greater value to the refinery, the yields (Figure 3) are expressed on a severity scale that combines the effects of both temperature and reaction time. The severity scale developed for use in this work on heavy stocks was the "equivalent reaction time a t 800' F." (For light stocks the equivalent reaction time at 900' F. is more convenient.) This is the calculated reaction time required to obtain the observed conversion if the reaction temperature was held constant at 800' F. The yields shown in Figure 3 are plotted against this severity scale in Figure 4. This scale correlates the data very nicely. In general, shaker bomb equivalent
50
800-
0
5
20
I5
IO
25
TIME I N MINUTES
800
' 6 600
0
5
I5
10
20
T I M E IN M I N U T E S
Figure 2.
Time-temperature pattern of shaker bomb experiments
reaction times of 200 to 800 seconds at 800' F. correspond to commercial visbreaking severities, while equivalent times above 800 seconds are in the range of commercial thermal cracking or coking severities. Although only small quantities of the individual products are recovered, these are sufficient for yield and for simple tests such as gravity and viscosity. This information is usually enough, when combined with experience, for an enconomic appraisal of whether or not the stock should be thermally processed in the refinery and for determining the optimum processing conditions. Determining Coke-Forming Tendencies. I n most visbreaking and in some thermal cracking operations, the greatest profit is realized when the process is operated at high severity; that is when the maximum amount of charge stock is converted per pass through the thermal unit. However, commercial processing severities are limited by the rate at which the furnace tubes are fouled by coke deposits. Such deposits cause both a reduction in heat transfer rates and an increase in pressure
drop across the furnace until the furnace must be shut down and cleaned. Because charge stocks differ widely in response to thermal conversion and in coke-forming tendencies, it is desirable to know these characteristics before a stock is charged to a commercial unit. The shaker bomb has proved to be a very useful means for obtaining this knowledge. As all of the coke formed is in the bomb a t the end of the experiment, either suspended in the liquid or deposited on the bomb wall? it may be recovered and weighed. The coke suspended in the liquid is separated from the liquid, dried, and weighed. The coke on the bomb wall is washed free of oil, dried, and weighed with the bomb. After weighing, the coke is removed by burning; the bomb is reweighed and is then ready for re-use. I n this way, the yield of coke is measured routinely along with the yield of gas and liquids in all shaker bomb thermal processing experiments Comparative conversions and cokeforming tendencies of three stocks are shown in Figure 5 . The conversion (Figure 5) is, by definition, 100% minus I
1
WT. %
-0
- 1
GASOLl N E (C4 -400 'E) VOL.
VOL.
%
DRY 6AS
1
0-0-
% 20
40
40
I
I
I 0-
1
VOL.
% 20
GAS O I L l(400 '750 O F . )
-
0-
0 loo
IO0
-
-
-0.
RESIDUUM (BOILING ABOVE 7 5 0 ~ ~ )
VOL. ?6 6 0
VOL.
% 60
40
40
20
t
20 0
-0 uAoL1 3
WT. 96
0 '
0
0
100
200 TIME,
400
300
'
800
1 "1 1
1200
'
1 1 1600
1
*2000
2400
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EQUIVALENT REACTION TIME AT 8OOOF.. SECONDS
500
Figure 4. Thermal cracking at 845" and 900" F. correlated to equivalent reaction time at 800" F. 0. 845OF.
SECONDS
Figure 3. Relative thermal cracking rates of a heavy petroleum fraction at 845" and at 900" F.
the per cent yield of liquid boiling above 750' F.; in this case, the conversion represents the proportion of charge reduced to lower boiling point. The three stocks (Figure 5) from a group of 14 stocks from one refinery, were separately evaluated in the shaker bomb for their thermal processing characteristics and their coke-forming tendencies. This information was required by the refinery to determine which stocks should be thermally cracked and what cracking severity should be used. The experimental data indicated that gas-oil yield, pour-point reduction, and viscosity reduction all increased steadily with increasing severity-that is, the best returns would be realized by processing the stocks a t the highest severity (highest conversion) possible while still maintaining acceptable furnace on-stream times. Thus the relative coke-forming tendencies, together with refractoriness (resistance to thermal conversion) (Figure 5 ) became a prime factor in the refinery's decision. Figure 5 shows that a stock such as the Venezuelan residuum cracks a t very mild severities to give large coke deposits, while another stock such as the TCC catalytic cycle stock requires very severe conditions and gives only moderate coke deposits. This illustrates that it is not desirable to blend stocks of different refractoriness and attempt to thermally crack them together. If this were attempted with these three stocks (Figure 5), tremendous quantities of coke would be obtained
400
0 . 900'
from Venezuelan residuum whereas the other two stocks would go through the cracking furnace practically unaffected. This conclusion was also confirmed in another company refinery processing both Venezuelan and Canadian crudes. Shaker bomb experiments with the Canadian residuum indicated that it would respond very well to thermal processing, requiring greater severity than the Venezuelan residuum but yielding relatively much less coke. In this case the refinery actually attempted to crack thermally a mixture of the two
F.
residua. Difficulties were experienced from the beginning of the commercial run with excessive furnace tube coking. Knowledge of the laboratory shaker bomb results enabled the refinery people to understand the source of the difficulty and led them to the separate processing. Pour-Point Reduction. The shaker bomb can also be used to determine optimum operating conditions for producing a material of specific physical properties, such as pour point or viscosity. For example, one of the company's refineries was producing a cat-
-
-3
I-
100 -
r g-
3
'20
I _ I 0
400
800
1200
I600
2000
2400
EQUIVALENT REACTION T I M E AT SOO'F.,
Figure 5.
2800
3200
3600
SECONDS
Coking tendencies of various petroleum stocks VOL. 50, NO. 1
JANUARY 1958
51
WT.
%
Y I E L D OF PRODUCT I N DESIRED BOILING RANGE
UPPER POUR POINT OF PRODUCT I N DESIRED BOILING RANGE
EQUIVALENT REACTION TIME AT 8OO'F.,
Figure 6.
Reducing pour point by thermal cracking
alytic cycle stock with a pour point of 9 5 " F.; this material was difficult to reduce further by catalytic cracking. A potential market for this material was available, provided the pour point could be reduced to 25 " F. The question arose as to whether the pour point could be reduced sufficiently by thermal processing to make the 25" F. pour point marketable product. The results obtained from the shaker bomb studies are shown in Figure 6. The material showed the refractoriness common to most samples of catalytic cycle stocks; that is, relatively high cracking severities were necessary before a reduction in pour point occurred. Because the coking tendency of the stock is low. however, it was concluded from the laboratory work that the required high severities would be commercially feasible. Data Reproducibility
The type of work using the shaker bomb has required good, but not precise, reproducibility in the data. The reproducibility shown in this table was good for almost all of the work. The yield data were obtained by treating two samples of the same typical thermal charge stock (which boiled above 750" F.) under the same shaker bomb conditions in separate experiments: Experiment Product Yields 1 2 Dry gas, % wt. 2.9 3.0 Gasoline (400' F. end point), 7 0 vol. 19.4 20.2 Gas oil (400-750' F. boiling range), vol. 40.2 41.4 Heavy liquid (boiling above 750" F.),% vol. 40.0 38.0 Coke, % wt. 0.37 0.34
If better reproducibility than this had been required, then much of the improvement could have been gained by refinements in the distillation methods used in obtaining yields.
52
SECONDS
INDUSTRIAL AND ENGINEERING CHEMISTRY
Correlation of Shaker Bomb with Pilot Plant and Commercial Units
The yields of the various products obtained in shaker bomb experiments correlate well with those obtained in continuous coil pilot plants and commercial units. However, the severity required to obtain corresponding product yields in the shaker bomb does not always correspond exactly with that estimated for the pilot plant or commercial unit. This is probably because it is almost impossible to define precisely
a range of severities (Figures 3 and 4) and the results are compared with similar experiments using stocks on which there i s commercial experience. Such comparisons indicate what is to be expected commercially with respect to maximum procesring severity, liquid yields, gas make, product properties, and the like. I n evaluating proposed changes in the operation of existing units, the laboratory data show what results may be expected from a given change in operating severity. The table below compares the commercial and shaker bomb results. I n this comparison for a given conversion, the product yields from the shaker bomb and a commercial unit correspond closely. However, the estimated severity of the commercial unit, expressed as an equivalent reaction time at 800" F., i s considerably less than that determined in the shaker bomb. If the commercial unit had a 6" F. higher average temperature than that indicated on the charts, or if the reaction time were 14 seconds longer than that estimated, these severities would have agreed exactly. The same sort of comparison is obtained for the shaker bomb and coil pilot plant data, as shown by the table below. The comparison is made on the same basis as the commercial comparison, but the charge stock is different.
Mixture of Heavy Vacuum Gas Oils and Tars Shaker Commercial bomb Product vields Gas, % wt. Gasoline (400' F. end point), % vol. Gas oil (4OO-75O0 F.), % vol. Heavy liquid (boiling above 750° F.), % VOI.
Coke, % wt.
Residuum from Fosterton Crude Pilot alant Shaker coil bomb
1.2 9.8 27.9
0.7 8.5 28.5
2.0 8.8 24.0
1.7 8.4 22.4
59.2
60.0 0.12
64.7
65.0 0.3
Not obtainable
Not obtainable
Equivalent reaction time at 800° F., sec. 480Q 590a 39OC 435d Estimated from commercial pressure-temperature-time records. I n this comparison, a reduction of Go F. in temperature or of 14 seconds in reaction time would have duplicated estimated severity of commercial unit. Estimated from pilot plant pressure-temperature-time records. I n this comparison, a reduction of 3' F. in temperature or of 8 seconds in reaction time would have duplicated estimated severity in pilot plant.
the reaction severity in a continuous coil pilot plant or commercial unit on account of uncertainties regarding phase relationships and volumes of the liquidvapor reaction mixture and uncertainties regarding effective reaction temperature, which together determine the timetemperature pattern. As with pilot plant work, an exact severity correlation between shaker bomb data and commercial operation is not necessary. I n evaluating unknown stocks, the laboratory work is done over
In general, the shaker bomb has proved to be a valuable new tool for the study of high temperature, high pressure reactions where good agitation, rapid heating, and rapid cooling are desired. As such, the shaker bomb technique may be of interest in industries other than petroleum. RECEIVED for review March 29, 1957 ACCEPTED July 5, 1957 Division of Petroleum Chemistry, 131st Meeting, .4CS, Miami, Fla., April 1957.
