INDUSTRIAL AND ENGINEERING CHEMISTRY
954
The wrought iron from this process compares favorably with any wrought iron produced today.
Anthracite and Slate as Fillers for Asphalt Because of the abundance of anthracite slate and the low cost a t which this material can be marketed, much work has been conducted on its use as a filler for asphalt. The slate analyzes as follows (in per cent by weight): Si02 Alios FezOa
20.18 10.65
1.21
CaO
MgO Alkalies
0.14 0.07 0.63
When ground to $40 mesh, the slate has a flat laminated structure. However, as the grinding continues to -200 mesh the flat particles disappear. The value of the slate as an asphalt filler is due to the overlapping of these flat particles which prevents movement within the asphalt. The sulfur content of some slates is also another factor hindering its use as an asphalt filler because sulfur will decrease the life of the asphalt. When the anthracite, ground to 315 Tyler mesh, was used as a filler in bituminous test bricks, weathering was greater than in bricks containing more standard fillers. Although the coal is easily wetted with bitumen and imparts the anticipated mechanical stability to the bituminous compound, it is inferior to other mineral fillers in weather resistance.
VOL. 27, NO. 8
This may be due to the permeability of the powdered coal to actinic light. A good grade of mineral filler will increase the life of the asphalt when exposed in the Weatherometer approximately 225 per cent; pulverized anthracite effects an increase of only 30 per cent. Coal has been used successfully as a filler for tar and asphalt in European paving.
Sintered Anthracite Slate as Concrete Aggregate The anthracite industry of Pennsylvania has millions of tons of refuse that could be used as an excellent concrete aggregate after sintering. Raw anthracite slate was crushed to -8 mesh and then sintered on a Dwight-Lloyd sintering machine carrying a 5inch bed of slate. The sintering time was 35 minutes because it was necessary to burn out practically all of the carbon before sintering occurred. The finished product was a hard, structurally strong, sintered mass that had to be crushed to whatever aggregate size was necessary. When prepared, however, this material was light in weight and very strong. The total weight of the concrete can be reduced by using this material, thus reducing the weight of the structural steel necessary in high structures. RECEIVED April 19,1935.
[ENDOF SY~~POSIKJM] .tC#
#)*a
W
HEN hydrocarbon gases are dissolved in liquid hydrocarbons, marked decreases in density, surface tension, and viscosity result. Such changes have an important bearing upon the processes involved in the production of crude petroleum. It is therefore of interest to obtain sufficient experimental information to permit the prediction of such changes as functions of the properties of original oil and gas involved, of temperature, and of equilibrium pressure. The present paper deals with results of a study of viscosity changes resulting from solution of methane and of propane in an oil known as crystal oil, under conditions of equilibrium temperature and pressure commonly met in petroleum production practice.
Materials and Apparatus The crystal oil used in this study was a water-white refined oil produced from a western crude stock. It was chosen as a suitable material on account of its stability, low vapor pressure, high viscosity, and narrow range of properties of its constituent hydrocarbons. The analysis and physical properties of this oil have been described in detail by Sage and co-workers (2). The methane supply was prepared from natural gas by methods previously outlined (2). Possible impurities consisted of nitrogen and similar inert gases to the extent of less than 0.2 per cent and of less than 0.02 per cent of hydrocarbons of higher molecular weight. The propane was of a chemically pure grade giving no evidence of impurities by fractionation analysis or by variation of equilibrium pressure during gradual condensation a t constant temperature ( 5 ) . All three of these materials have also been utilized in connection with phase-equilibrium studies of hydrocarbon systems (3,4,6) and it is therefore possible to obtain information concerning additional properties to those discussed in this paper. The viscometer used for the measurement of viscosity of saturated solutions was that described by Sage (I). It con-
Viscositv of d
Hydrocarbon Solutions Solutions of Methane and Propane in Crystal Oil B. H. SAGE, J. E. SHERBORNE,
AND W. N. LACEY
California Institute of Technology, Pasadena, Calif.
sisted in principle of a ball rolling down an inclined tube filled with the saturated solution under controlled conditions of saturation pressure and temperature. Since the densities of these saturated solutions were known from studies in other apparatus (9, d ) , the density balance formerly described as part of the viscometer circuit was eliminated, thus decreasing the amount of materials needed to fill the apparatus. The density measurements referred to furnish more accurate re-
INDUSTRIAL AND ENGINEERING CHEMISTRY
AUGUST, 1935
sults than those obtained by the density balance, and their use therefore serves to increase the accuracy of the absolute viscosity values The saturation pressures were measured by means of a mercury manometer up to a pressure of 50 pounds per square inch absolute. From that pressure to 300 pounds per square inch a fluid-pressure scale reading to 0.1 pound per square inch was used. From 300 to 3000 pounds per square inch, a second fluid-pressure scale reading to 1 pound per square inch was utilized. After the oil sample had been placed in the viscometer unit, the whole system was evacuated to a pressure less than 0.03 inch (1 mm.) of mercury column to remove air. This could be done without appreciable loss of oil since its vapor pressure was only about one-hundredth of this pressure a t room temperature. I n the case of the methane studies, care was exercised to use the same amount of oil for each determination so that transfer of oil to the gas phase near the region of critical phenomena might be into a constant volume of gas c!-p ace. The propane solutions increased in volume to such an extent, as the pressure was increased, that portions of the solution had to be removed during the run, resulting in variations of TABLE I. VISCOSITY OF SATURATED METHANESOLUTIONS Ahs. Pressure, Lb./Sq. ' In. 100° F.
Ahs. Viscosity, Millipoises 130' F. 160' F. 190° F. 137.6 120.8 107.2 94.3 84.1 74.6 65.2 57.4 51.8 46.8 39.7 34.8
I
I
955
I 140
eo
TEMPERATURE
FIGURE2, EFFECTOF
I
1
BO
180
200
D E G . F.
SATURATION TEMPER.4TURE
ON V I S -
METHANESOLUTIONS
COSITY OF
220° F.
the volume of gas space. However, these mixtures were sufficiently far removed from critical states so that no appreciable transfer to the gas phase would occur.
Experimental Results The viscosity of saturated solutions of methane in crystal oil has been measured a t 5 temperatures from 100" to 220" F.
I
I
IC0
125
I 150
TEMPERATURE
I
175
I
200
DEG. F.
FIGURE3. VISCOSITY OF METHANESOLUTIONS OF CONST.4NT COMPOSITION AT DIFFERENT TEMPERATURES
I
I 500
1000
PRESSURE
1500
2000
2500
L B S P E R S Q IN
FIGURE1. EXPERIMESTAL CURVESFOR VISCOSITYOF SATURATED h f E T H . 4 N E SOLUTIONS
and for saturation pressures up to 3000 pounds per square inch absolute. These experimental results are shown in Figure 1. Viscosity values are also shown in Table I a t convenient values of temperature and pressure. The necessary data for the densities of these solutions were taken from phaseequilibrium studies upon the same materials previously reported (2). These density data may be used in case kinematic viscosity values are desired instead of the absolute viscosity values here given. The effect of temperature upon the viscosity of solutions saturated a t constant pressure is shown in Figure 2. These solutions vary in composition as the temperature changes. However, the results can be shown for constant composition by making use of the phase-equilibrium results already mentioned (2). Such constant-composition curves are shown in Figure 3. The less rapid decreases in
ISDUSTRIAL AND ENGINEERING CHEMISTRY
956
VOL. 27, NO. 8
v)
w
L"
zA
E
z >
c
0
U
I? w
c 3
J 0 ul
m
I
120
140
FIGURE5. EFFECTS OF COSITY OF
250
1
~
125
150
\
J
I
100
TEMPERATURE
_
_
175
_
~
~
-
~
a3 25 50 75 100 150 200 260
100' F. 283.8 114.5 80.0 40.9 22.6 11.8
200
... ...
...
PROPANE SOLUTIONS
Acknowledgments These studies were carried out as part of the work of Research Project 37 of the American Petroleum Institute. The authors acknowledge encouragement and financial assistance from the institute. Thanks are due H. S. Backus for assistance in the computations.
VISCOSITY OF SATURATED PROPANE SOLUTIONS
130' F. 137.6 85.0 57.4 40.8 28.9 14.4 (9.6)
SATURATION TEMPERATURE ON VIS-
D E G . F.
viscosity in Figure 2 are due to the effect of smaller solubility .of the gas a t higher temperature which partly compensates for hhe decrease of viscosity with temperature. TABLE11.
200
DEG. F.
The viscosity of saturated solutions of propane in crystal oil has been studied a t seven temperatures ranging from 100" to 220' F. for saturation pressures up to 70 per cent of the -vapor pressure of propane a t each temperature. The experimental results for three of the temperatures are shown in Figure 4,the other curves being omitted for the sake of clarity of the graph. The complete set of results, aside from some for 200' F. previously shown graphically (4), is given in Table 11. Excellent agreement was found between the present results and those measured some time earlier. The viscosity curves of Figure 5 are for constant saturation pressure, with variable composition as the temperature changes. The peculiar increase of viscosity with increase of temperature in one part of this diagram is due to more rapid decrease of solubility with increase of temperature than would be necessary to counterbalance the effect of temperature upon viscosity of a given solution. This ''overcompensation" occurs only through a limited pressure-temperature region. Figure 6 shows viscosity curves for constant composition, saturation pressures being in this case variable with temperature. The pressure-volume-temperature relations needed to construct this figure were obtained from an earlier publication ( 4 ) .
OF PROPANE SOLUTIONS OF COXSTANT FIGURE 6. VISCOSITY COMPOSITION AT DIFFERENT TEMPERATURES
Abs. Pressure, Lb./Sq. In.
180
160
TEMPERATURE
-4bs. Viscosity, Millipoises 140' F . 150' F. 160' F. 79.8 114.7 95.9 64.2 73.9 80.3 50.4 57.3 68.0 41.4 42.9 44.0 33.1 33.7 32.2 20.7 19.6 17.0 10.4 11.5 12.6 (5.) (6.) (7.)
190'F. 47.4 40.3 36.3 32.3 27.8 20.6 14.7 (9.6)
220' F. 32.4 29.6 27.2 24.9 22.5 18.7 15.5 12.4
Literature Cited (1) Sage, B.H., IND. ENCI.C H E M . Anal. , Ed., 5, 261 (1933). ( 2 ) Sage, B. H., Backus, H. S., and Lacey, TV. N., I K D . ESQ.C H E M . 27, , 686 (1935). (3) Sage, B. H.,Lacey, W. N., and Schaafsma, J. G., Ibid., 26, 214 (1934). (4) I b i d . , 26,874 (1934). (5) Ibid., 26,1218 (1934).
RECEIVED March 25. 1935.
