Subscriber access provided by UNIV TORONTO
Article
Experimental Investigation on the Interaction Forces between Clathrate Hydrate Particles in the Presence of a Water Bridge Chenwei Liu, Mingzhong Li, Litao Chen, Yuxing Li, Sixu Zheng, and Guangming Han Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.7b00364 • Publication Date (Web): 10 Apr 2017 Downloaded from http://pubs.acs.org on April 16, 2017
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
Energy & Fuels is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 23
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
1
Experimental Investigation on the Interaction Forces between Clathrate
2
Hydrate Particles in the Presence of a Water Bridge
3
Chenwei Liua,b, Mingzhong Lia*, Litao Chena, Yuxing Lib, Sixu Zhengc, Guangming Hand* a
4
College of Petroleum Engineering, China University of Petroleum, Qingdao 266580, China b
5
Shandong Provincial Key Laboratory of Oil and Gas Storage and Transportation, China University of Petroleum, Qingdao 266580, China
6 7
c
Petroleum Systems Engineering, Faculty of Engineering and Applied Science, University of Regina, Regina, S4S 0A2, Canada
8 9
d
Science and Technology Development and School-Enterprise Cooperation Section, Chengde Petroleum College, Chengde 067000, China
10 11
Corresponding Authors:
12
Mingzhong Li
E-mail:
[email protected] 13
Guangming Han
E-mail:
[email protected] 14 15 16 17 18 19 20 21 22 23 1
ACS Paragon Plus Environment
Energy & Fuels
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
24
ABSTRACT
25
The agglomeration of hydrate particles is one of the main causes of hydrate accumulation or bedding in oil
26
and gas pipelines. The unconverted water droplets in the system play a crucial role in hydrate particle
27
agglomeration. In this study, a novel technique was developed to directly measure the interaction forces between
28
cyclopentane hydrate particles with a water bridge between them by using a micromechanical force (MMF)
29
apparatus. On the basis of the developed method, the interaction forces at different temperatures and water bridge
30
volumes and the effects of mineral oil were experimentally studied. At a low subcooling level of 1.7 °C, the
31
contact areas and adhesion forces between the hydrate particles and water droplets increased with the increase in
32
the water droplet volume. For the case of a higher subcooling level of 6.2 °C, rapid hydrate formation between the
33
bridging water droplets prevented the hydrate particles from being effectively wetted, resulting in a small contact
34
area. There was no clear relationship between the contact area/adhesion force and the water droplet volume. The
35
hydrates formed on the water bridge could dramatically strengthen the adhesion force, while the addition of
36
mineral oil in cyclopentane could retard the water droplets from converting into hydrates, consequently decreasing
37
the adhesion force. The measured adhesion forces between the hydrate particles and water droplets may provide
38
further insight into the hydrate agglomeration process.
39
Key words: hydrate agglomeration, micromechanical force apparatus, adhesion force, unconverted water droplet,
40
hydrate particle
41 42
INTRODUCTION
43
Gas clathrate hydrates are crystalline inclusion compounds comprised of hydrogen bonded water cavities that
44
encapsulate suitably sized gas molecules (e.g., methane, ethane, propane, and carbon dioxide) at appropriate
45
pressures and temperatures.1-3 As gas and oil exploration and production move to ultradeep water (>8000 ft of sea
46
water), the oil and gas production pipelines provide favorable conditions (i.e., high pressure and low temperature) 2
ACS Paragon Plus Environment
Page 2 of 23
Page 3 of 23
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
47
for gas hydrate formation. The aggregation and accumulation (or bedding) of hydrates in pipelines can lead to
48
pipeline blockage, resulting in catastrophic operational failures and safety hazards to personnel and equipment,
49
thereby presenting a major flow assurance issue in oil and gas pipelines.1 Therefore, it is of fundamental and
50
practical importance to investigate and understand the agglomeration mechanism of hydrates in pipelines.
51
For an oil-dominated system, a conceptual model with four successive steps has been proposed for describing
52
hydrate plug formation in pipelines.4 The proposed model suggests that hydrate agglomeration is the limiting
53
factor during plug formation.1 In fact, hydrate agglomeration processes can be considered as analogous to wet
54
granulation processes. In the pharmaceutical industry, granulation/agglomeration technology has been widely
55
employed, which refers to acts or processes in which primary powder particles are made to adhere to form larger
56
multiparticle entities called granules.5 In particular, as one of the major granulation technologies applied in the
57
pharmaceutical industry, wet granulation processes involve adding a liquid solution/binder to powders, forming
58
bonds between the powdered particles.6 The whole process can be regarded as a combination of four sets of
59
processes (see Figure 1):7-9 (i) spraying, in which liquid binder is added to the system, and the diameters of the
60
binder can vary from dozens to thousands of microns;10 (ii) moistening, in which the liquid binder is brought into
61
contact with a dry powder, forming granules; (iii) consolidating, in which collisions between two granules or
62
granules and feed powder lead to granule compaction; and (iv) growing. In oil and gas pipelines, emulsified water
63
droplets in crude oil typically have a mean diameter between 20–80 µm.11 When some water droplets convert into
64
hydrate particles, as expected, the unconverted droplets can serve as the added liquid solution/binder, while the
65
water–wet hydrate particles will play the role of powders during wet granulation. However, the water droplet will
66
gradually convert into a solid hydrate during the agglomeration process, resulting in more complex hydrate
67
agglomeration than conventional wet granulation. Although wet granulation provides evidence of the crucial role
68
of unconverted droplets during the granulation/agglomeration process, multiple studies to date have merely
69
focused on dry hydrate–hydrate particle interactions.12-17 It has been found that the adhesion forces between dry 3
ACS Paragon Plus Environment
Energy & Fuels
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 4 of 23
Wet granulation process
Powder
Spraying
Consolidating
Moistening
Growing
Hydrate 70 71
Hydrate agglomeration process Figure 1. Schematic of the wet granulation/ proposed hydrate agglomeration process
72 73
hydrate particles are much smaller and are hard to account for regarding the remarkable hydrate agglomeration
74
tendency observed in real oil-gas pipelines.18 In addition, the interactions between dry hydrate particles also
75
confirm the critical role of unconverted water (i.e., quasi-liquid layer) in the adhesion force.12,16 Recently, Song et
76
al.,19-20 Cha et al.21 and Liu et al.8 investigated the interaction between a hydrate particle and a water droplet,
77
which can be regarded as studies on the moistening process during hydrate agglomeration. During their
78
measurements, the liquid droplets had to be placed on flat plates. As suggested by previous experimental studies,
79
the characteristics of the flat plates (e.g., roughness and wettability) will affect the interaction behavior/force.19, 22
80
Fidel-Dufour et al.23 suggested that hydrate agglomeration occurs through three-body collisions between one
81
unconverted water droplet and two already formed agglomerates/particles due to high crystal and droplet
82
concentrations. However, to the best knowledge of the authors, few attempts in the literature have been made to
83
investigate the important hydrate-droplet-hydrate adhesive interactions during hydrate agglomeration.
84
In our previous work, we studied the interactions between hydrate particles and water droplets placed on a
85
flat plate using a micromechanical force (MMF) apparatus.8 To eliminate the interference of the plate, in this study, 4
ACS Paragon Plus Environment
Page 5 of 23
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
86
we proposed a novel procedure to directly measure the cyclopentane hydrate particle-water droplet-hydrate
87
particle interactions. On the basis of the procedure, the hydrate-droplet-hydrate interactions were experimentally
88
investigated, and the effects of temperature, water droplet volume and mineral oil were discussed, which provided
89
deeper insight into the hydrate agglomeration process.
90 91
EXPERIMENTAL SECTION
92
Chemicals
93
Cyclopentane (CyC5) was used as a model hydrate former under atmospheric pressure because it is stable up
94
to 7.7 °C at ambient pressure.1 Furthermore, CyC5 is superior to other ambient pressure hydrate formers (e.g.,
95
tetrahydrofuran) because CyC5 is immiscible in the aqueous phase and forms structure II hydrates, which are
96
usually encountered in petroleum fields. The CyC5 (98% purity) used in this work was purchased from Fisher
97
Scientific UK Ltd. Mineral oil 70T (STE Oil Company, Inc.) with a density of 0.857 g/cm3 at 20 °C was used in
98
this study, and the compositional analysis of mineral oil 70T can be found elsewhere.8
99 100
Interaction measurement procedures
101
A micromechanical force apparatus developed by the Colorado School of Mines Center for Hydrate Research
102
was used for measuring the CyC5 hydrate particle-water droplet-hydrate particle interactions. The MMF apparatus
103
includes a Zeiss S100 inverted light microscope that is encased in a dry box with a mean relative air humidity
104
lower than ~20%. The microscope stage holds an aluminum cell (see Figure 2) that is surrounded by a cooling
105
jacket connected to an external refrigeration unit (1196D, VWR International, Inc.). A circular cover glass was
106
placed on the bottom of the cell for visualization. The experimental cell was filled with liquid CyC5 and housed
107
two cantilevers. One cantilever was connected to a manual micromanipulator, while the other cantilever was
108
connected to a remotely operated micromanipulator (Eppendorf Patchman 5173). The MMF system has been 5
ACS Paragon Plus Environment
Energy & Fuels
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 6 of 23
CyC5 Aluminum Rod
Microcapillary Tube
Glass Fiber
109 110
Flat Plate
Glycol Cooling Jacket
Cover Glass
Figure 2. The experimental cell setup for the hydrate particle and water droplet interaction measurements.
111 112
extensively used to measure hydrate-hydrate interaction forces.12-17 Recently, the interaction between a hydrate
113
particle and a water droplet was also investigated using the MMF system.8 A more detailed description of the
114
experimental system can be found elsewhere.8, 16-17 To conduct the measurements, the droplet had to be placed on
115
a flat plate, and the characteristics of the plate (e.g., roughness) would affect the experimental results.19 Herein, in
116
order to eliminate the interference of the plate, on the basis of previous observations, the following procedures
117
were proposed for directly measuring the hydrate particle-droplet-particle interactions.6 The entire measurement
Epoxy-A Droplet Glass fiber
Ice
(a)
(g)
(h)
118 119 120 121
Hydrate
Liquid N2 (b)
(c)
(e)
(f)
(j)
(i)
(d)
(k)
Figure 3. Schematic of the proposed experimental procedure to directly measure the hydrate particle-water droplet-hydrate particle interactions. The procedures in the red dotted lines indicate the measurements that were conducted in liquid CyC5.
122 6
ACS Paragon Plus Environment
Page 7 of 23
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
123
process included four successive steps (see Figure 3): (i) Generate two hydrate particles (Figures 3a–c). The
124
dropper technique was used to form a droplet on the end of each glass fiber cantilever (diameter: approximately
125
38 µm),8 and one droplet was then transferred from one glass fiber to the Epoxy-A-coated layer in air (Figure 3a).
126
The two droplets were quenched in liquid nitrogen for 20 s to completely convert them into ice particles (Figure
127
3b). The ice particles were placed immediately into the CyC5 bath (maintained at -5 °C) within 2 s. The liquid
128
CyC5 temperature was then slowly increased above the ice freezing temperature (0 °C) with a heating rate of
129
0.1 °C/min, allowing the ice particles to convert into CyC5 hydrate particles (Figure 3c). At the experimental
130
temperatures (i.e., 1.5 °C and 6 °C), the hydrate particles were immersed in the CyC5 cell for 30 min. (ii) Mount a
131
droplet on the plate. The same dropper technique was used again to form a water drop on the end of the other glass
132
fiber (spare) cantilever. The water droplet was then transferred from the glass fiber (spare) cantilever to the
133
Epoxy-A-coated plate immersed in the CyC5 cell with a contact angle of 136.44±2.77 ° (Figure 3d). (iii) Generate
134
a hydrate-droplet dimer. The position of the plate (Figure 3e) was adjusted while contacting the droplet and
135
hydrate particle on the stationary glass fiber (Figure 3f). The plate was then retracted quickly. As a result, some of
136
the water was left on the hydrate particle on the fiber, forming a hydrate particle-droplet dimer (Figure 3g). Quick
137
retraction could reduce the amount of liquid water that was converted into the solid hydrate, especially at a lower
138
temperature (i.e., higher subcooling). (iv) Measure the hydrate particle-droplet-hydrate interactions. Adjust the
139
position of the plate quickly (Figure 3h), and then, begin the measurement. The measurement procedure included
140
“approaching” and “retracting”. During the approaching process (Figures 3h and i), the hydrate particle on the
141
plate was slowly brought into contact with the hydrate particle-droplet dimer on the glass fiber, creating a preload
142
force. During the retracting process, the hydrate particle on the plate moves away from the other hydrate particle
143
slowly until the hydrate particle-droplet-hydrate particle complex detaches (Figures 3j and k). The displacement of
144
the glass fiber cantilever during the measurement was captured in real time at 30 frames per second. The
145
displacement was multiplied by the cantilever spring constant (i.e., Hooke’s law) to determine the interaction 7
ACS Paragon Plus Environment
Energy & Fuels
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
146
Page 8 of 23
force between the hydrate particles and droplets.
147 148
RESULTS AND DISCUSSION
149
With the aforementioned procedure, the interactions between the CyC5 hydrate particles and water droplets
150
in pure CyC5 at 6 °C (i.e., subcooled by 1.7 °C) were measured. The experimental results are shown in Figures 4
151
and 5. Figure 4 shows the microscope images of the preparation processes before the final measurements. In
152
Figure 4a, two ice particles, which were placed on the glass fiber and flat plate, respectively, were immersed in
153
CyC5. As the liquid CyC5 temperature was slowly raised above the ice-freezing temperature, the ice particle on
154
the plate dissolved first and converted into a hydrate particle. The other ice particle on the glass fiber then
155
dissolved and formed a hydrate particle (Figure 4c). After a period of 30 min of annealing at 6 °C, a droplet was
156
introduced onto the plate with another glass fiber (spare) cantilever (Figure 4d). Figures 4e and f show the
157
formation process of the hydrate-droplet dimer, and hydrate was not visibly formed from the droplet due to the
158
much lower subcooling level (i.e., 1.7 °C).
Ice
Ice
Hydrate
Hydrate
a
b
c
d
e
f
Droplet
159 160 161 162
Figure 4. Microscope images of hydrate particles and hydrate particle-droplet dimer formation at 6 ºC. The black moon shape shadow on the top part of the droplet is the shadow of the flat plate on it.
163
Figure 5 shows the hydrate-droplet-hydrate interaction force as a function of the plate displacement, together
164
with the respective microscope images. Before the interaction, the plate was adjusted to set the positions of the
165
hydrate particle and hydrate-droplet dimer, as shown in Figure 5A. The plate then slowly approached the hydrate
166
particle-droplet dimer, and no measurable net interaction force acted upon the two surfaces until point B, in which 8
ACS Paragon Plus Environment
Page 9 of 23
10 51.4 s
0s
200 µm
I
Interaction Force/µN
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
200 µm
4.6 s
200 µm
0 C
-10 7.5 s 51.0 s
-20
19.8 s
200 µm
E 32.6 s
168 169
-400
200 µm
200 µm
G
-30 -600
200 µm
200 µm
H 44.0 s
167
D
B
Approaching A
Retracting
F -200 0 Plate Displacement/µm
200
400
Figure 5. Typical interaction force curve of the CyC5 hydrate particle-water droplet-hydrate particle interaction in pure CyC5 at 6 °C. The images at various key locations are shown to help interpret the force curve.
170 171
the droplet rapidly spread on the top hydrate particle surface. A hydrate-CyC5-water three-phase-contact (TPC)
172
line was formed and pinned on the top hydrate particle surface, resulting in a rapid drop in the interaction force
173
from point B to C (initial contact force), which was ascribed to the hydrophilic properties of the hydrate particle.
174
As shown in Figure 5C, the original droplet then behaved as a liquid bridge that bonded the two hydrate particles.
175
As the plate continued to approach the bottom hydrate particle, the liquid bridge gradually changed from a
176
stretching to a compression state. Correspondingly, the interaction force between the particles shifted from an
177
attractive force to a repulsive force. At point D, the repulsive force reached the set value (preload force: ~12 µN).
178
Once the preload force was reached, the plate retracted away from the bottom hydrate particle. The interaction
179
force first presented an approximately straight line (D to E), and then, it curved from point E to F because of the
180
large liquid bridge deformation. At point F, the interaction force reached the maximum level (i.e., adhesion force:
181
~31 µN) and remained constant until point G. After the plateau, the interaction force began to decrease when the
182
liquid bridge was stretched further, and necking occurred in the liquid bridge. Finally, at point H, a significantly 9
ACS Paragon Plus Environment
Energy & Fuels
183
narrow neck formed, and the liquid bridge ruptured at the neck. The liquid bridge was distributed between the two
184
hydrate particles, and the shape of the droplets was approximated as a perfect sphere. During the entire
185
measurement process, both TPC lines were pinned on the hydrate particle surface due to strong wetting hysteresis
186
between the CyC5 hydrate and water.24 Furthermore, the outlines of the liquid bridge intersecting with the hydrate
187
particles presented a smooth curve, which suggests that hydrate was not visibly converted from the liquid bridge
188
under this condition.
40 Interaction force/µN
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 10 of 23
200 µm
200 µm
30
Cycle 1
Cycle 2
200 µm
Cycle 3
200 µm
Cycle 4
20
10
0
189 190 191 192 193 194
Rupture force
Maximum force
Figure 6. Reproducibility measurements of the hydrate particle-water droplet-hydrate particle interaction forces at 6 °C. The hydrate was not visibly converted from the liquid bridge during the measurement. The coefficient of variation of the forces was less than 3%.
195
The rupture of the original liquid bridge led to the formation of two hydrate-droplet dimers. Then, the same
196
approaching-retracting procedure was repeated three times for the two hydrate-droplet dimers, and the results are
197
shown in Figure 6. The maximum interaction force and rupture force exhibited good repeatability, and the
198
coefficients of variation of the forces were less than 3%. The corresponding images also suggest that the amount of
199
liquid distributed to the hydrate particles was approximately same for the four test cycles. The high repeatability
200
confirmed the reliability of the experimental apparatus and measurement procedure. Meanwhile, the repeatability
201
further implies that the total liquid amount remained approximately constant during the entire measurement at 10
ACS Paragon Plus Environment
Page 11 of 23
202
6 °C, that is, hydrate was not visibly converted from the liquid bridge. In the literature, the adhesion force between
203
dry hydrate particles has exhibited considerable variability.12-17 As suggested by Yang et al.,12 the variability arises
204
because the nanoscale surface asperities have a slightly different alignment during each repeated contact, and a
205
given surface roughness distribution therefore leads to a probabilistic distribution of the measured forces. In this
206
study, the presence of the water droplet on the hydrate particle surface submerged all the asperities and prevented
207
direct contact between the dry hydrate particles, thereby eliminating the variability resulting from the surface
208
roughness.
209
10 20.8 s
200 µm
A
Approaching
1.2 s
B
200 µm
D
0 C
-10
4.5 s 1.7 s
-30 -600
200 µm
200 µm
E
-20 G
210
0s
200 µm
H
Interaction Force/µN
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
19.4 s
200 µm
12.6 s
F
200 µm
Retracting
-400
-200 Plate Displacement/µm
0
200
211 212 213 214
Figure 7. Typical force curve of the CyC5 hydrate particle-water droplet-hydrate particle interaction in pure CyC5 at 1.5 °C. The red lines in the images denote the TPC line. The images indicate the amount of liquid water converted into solid hydrate during the measurement.
215
The temperature/subcooling was found to play an important role in the dry hydrate-hydrate and
216
hydrate-droplet interactions.8,12,16,24 Herein, corresponding to Figure 5, the interaction behavior in pure CyC5 at a
217
lower temperature (1.5 °C, i.e., at a subcooling level of 6.2 °C) is shown in Figure 7. During the preparation
218
process of the hydrate particle-droplet dimer, although the proceeding time was reduced as much as possible, a
219
significant amount of water was still converted into hydrate due to the high level of subcooling and induction of 11
ACS Paragon Plus Environment
Energy & Fuels
220
the bottom hydrate particle (Figure 7A). At point B, the droplet contacted the top hydrate particle and
221
subsequently spread on the particle surface. However, due to the high subcooling level, the water molecules
222
around the TPC line tended to rapidly form additional hydrates that prevented the effective wetting of water on the
223
top hydrate particle. As shown in Figure 7C, the contact area between the droplet and top hydrate particle was
224
quite small despite the relatively large droplet volume. In the subsequent measurements, the hydrate continued to
225
grow from both boundaries toward the middle. As indicated in Figure 7F, a significantly raised hydrate platform
226
evolved around the contact region of the liquid bridge and top hydrate particle. Finally, the liquid bridge broke,
227
and a small amount of water was distributed to the top hydrate particle due to the relatively small contact area
228
between the liquid bridge and top hydrate particle. Meanwhile, a large part of the droplet left on the bottom
229
hydrate particle was encased by the hydrate shell.
230 231
30 104.3 s
0s
200 µm
I
200 µm
Approaching
7.7 s
200 µm
C
A
0 D
Interaction Force/µN
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 12 of 23
B
-30 0.7 s
200 µm
-60 69.0 s 90.2 s
F
-90 -120
F
200 µm
E
200 µm
84.4 s
200 µm
Retracting
-150 -800 232
-600
-400 -200 Plate Displacement/µm
0
200
233 234 235 236
Figure 8. Typical hydrate particle–water droplet-hydrate particle interaction force profile in which the hydrate shell fully wrapped the liquid droplet before the “retracting” phase. The test temperature was 1.5 °C. The purple circles are used to emphasize the deformation/ collapse of the hydrate shell.
237
To highlight the effects of the hydrate formation, the following measurements were performed (see Figure 8). 12
ACS Paragon Plus Environment
Page 13 of 23
238
Before retraction, the particles and droplet were allowed to rest under a constant preload force to allow the hydrate
239
shell to fully cover the liquid bridge (C to D, ~61 s). As indicated in Figure 8D, since the hydrate shell grew from
240
two opposite directions, a remarkable nucleation trace was formed near the middle of the liquid bridge. During the
241
retraction process, the convex hydrate bridge between the particles first maintained its original shape for a
242
relatively low pull-off force. With the further increase in the pull-off force, the hydrate bridge became unstable,
243
and one side of the bridge collapsed (see Figure 8E). The entire retraction force curve presents a linear region due
244
to the relatively small deformation of the solid hydrate bridge. Meanwhile, the corresponding adhesion force was
245
increased significantly (~150 µN) because the tensile strength of the hydrate shell governed the interaction force.
246
After the rupture of the hydrate bridge, the original collapsed hydrate shell retrieved its shape and became
247
spherical because of the capillary force. These phenomena suggest that although the liquid water was covered by
248
the solid hydrate shell, the strength of the hydrate shell under these conditions was not sufficiently strong to resist
249
the deformation resulting from the capillary force.
10 53.9 s
200 µm
I
Interaction Force/µN
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
0s
200 µm
Approaching
0
A
1.5 s
200 µm
B
-10
D
C 13.3 s 1.8 s
-20
200 µm
200 µm
E
-30
H
41.8 s
200 µm
G 28.8 s
F
-40 -600 250 251 252 253 254
-400
200 µm
Retracting
-200 0 Plate Displacement/µm
200
400
Figure 9. Typical interaction force curve of the CyC5 hydrate particle-water droplet-hydrate particle interaction in a 50 wt% CyC5 and 50 wt% mineral oil 70T mixture at 1.5 °C. The images suggest that hydrate was not visibly converted from the liquid droplet during the measurement.
13
ACS Paragon Plus Environment
Energy & Fuels
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 14 of 23
255
Previous studies on dry hydrate particle-particle interactions suggested that the addition of mineral oil to
256
CyC5 (1-50 wt%) did not have a significant effect on the hydrate morphology and cohesion force.15 Figure 9
257
shows the force behavior of the hydrate particle-droplet-particle interaction in a mixture of CyC5 and mineral oil
258
70T (mass ratio 1:1) at 1.5 °C. Compared with Figure 5, the hydrate was not visibly converted from the liquid
259
bridge throughout the entire measurement despite having the same bath temperature, suggesting that the addition
260
of mineral oil decreased the hydrate formation rate, which was attributed to the reduction in the subcooling level.8
261
A previous study and Figure 8 indicated that hydrate formation during the measurement would increase the
262
adhesion force between the hydrate and droplet.8 Thereby, the addition of mineral oil could decrease the adhesion
263
force.
264
For the water-in-oil emulsions, the sizes of the droplet were not uniform and presented polydispersity, e.g., a
265
normal or log-normal distribution.25 Understanding the effects of the liquid volume of the droplet on the
266
interaction force provided important insight into the agglomeration process. Figures 10a and b show the images
267
before and after the formation of the hydrate-droplet dimer, respectively. The liquid volumes of the droplets
268
(spherical cap) on the plate were calculated using the following equation:
269
6 2
270
(1)
where is the volume of the droplet on the plate and R is the apparent radius of the droplet.
271
h R
272 273
200 µm
200 µm
Figure 10. Images (a) before the droplet contacted the hydrate particle and (b) after the liquid droplet ruptured.
274
14
ACS Paragon Plus Environment
Page 15 of 23
p u re C yC 5 , T = 6 ℃ p u re C yC 5 , T = 1 .5 ℃
400000 350000
Contact Area/µm
2
300000 250000 200000 150000 100000 50000 24 0 pu re C yC 5, T= 6 ℃ pu re C yC 5, T= 1.5 ℃
21 0 Normalized Ahesion Force/mN/m
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
18 0 15 0 12 0 90 60 30 0 0.0
0 .3
0 .6
0.9 1.2 V d/V p
1.5
1.8
2.1
275 276 277
Figure 11. Hydrate particle-water droplet contact area and normalized adhesion force versus the volume ratio of the droplet to hydrate particle at different temperatures. The normalized force refers to the adhesion force divided
278
by the harmonic mean radius of the hydrate particle pair, ∗, where
∗
.
279 280
The original volume of the liquid bridge bonding the two hydrate particles was equal to the volume difference
281
between the droplets on the plate in Figures 10a and 10b. Figure 11 shows the effects of the water volume on the
282
contact area and the normalized adhesion force between the hydrate particles in pure CyC5 at 1.5 and 6 °C. For
283
the measurements at 6 °C, at a relatively lower Vd/Vp, the increase in the contact area with the water volume was
284
very slow. In addition, the contact area then increased dramatically with the further increase in the water volume.
285
Correspondingly, the adhesion forces presented a similar tendency with the contact areas. A similar phenomenon
286
was also reported in the experiments conducted by Cha et al..19 Compared to the measurements at 6 °C, the
287
hydrate-droplet contact areas in the measurements at 1.5 °C were quite scattered. There was no clear relationship
288
between the contact area and water volume. Furthermore, the contact areas from the measurements at 1.5 °C were
289
generally significantly smaller than those from the measurements at 6 °C. Both phenomena were attributed to the 15
ACS Paragon Plus Environment
Energy & Fuels
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 16 of 23
290
higher hydrate formation rate at 1.5 °C. As aforementioned, once the droplet contacted the hydrate particle, a
291
higher subcooling/driving force promoted the water molecules around the TPC line to rapidly form additional
292
hydrates. The additionally formed hydrates prevented the effective wetting of water on the hydrate particle surface,
293
resulting in a smaller contact area. In addition, due to the formation of the additional hydrates, the effects of the
294
water volume on the contact area were disturbed by the high hydrate formation rate. Corresponding to the
295
scattered contact areas, the adhesion forces were also scattered. Furthermore, although the contact areas from the
296
measurements at 1.5 °C were significantly smaller than those from the measurements at 6 °C, the corresponding
297
adhesion forces at 1.5 °C were larger than those from the measurements at 6 °C. As aforementioned, the hydrate
298
formation from the liquid water could strengthen the adhesion forces between the hydrate particle and droplet.
299
For oil dominated systems, the agglomerations of the hydrate particles and droplets were porous. Since the
300
aggregates in the fluid acted hydrodynamically like compact spheres, screening the amount of oil (continuous
301
phase) in the interior from the outside, an effective hydrate volume fraction was considered instead of the real
302
volume fraction. The effective hydrate volume fraction can be written as 26
303
(2)
304
where is the effective hydrate volume fraction, is the real volume fraction, RA is the radius of the
305
aggregates, R is the radius of the particle/droplet, and fr is the fractal dimension of the aggregates.
306
Figures 7 and 11 suggest that at high level of subcooling, a high hydrate formation rate prevented the
307
effective wetting of water on the hydrate particle surface, thereby resulting in a smaller contact area. Consequently,
308
it tended to form loose aggregates, resulting in a smaller fr. Furthermore, according to the fact that the aggregate
309
size depended on the balance between the shear stress and adhesion force between the particles, a larger adhesion
310
force tended to generate larger aggregates. Both the smaller fr and larger aggregate size led to a larger effective
311
hydrate volume fraction. Therefore, the viscosity of the hydrate slurry was higher at a higher subcooling
312
level/lower temperature. Such findings are in accordance with the results of Webb et al..27, 28 They investigated the 16
ACS Paragon Plus Environment
Page 17 of 23
313
effects of the initial pressure and temperature on the rheological properties of methane hydrate slurries formed
314
from water-in-oil emulsions. They found that both the hydrate slurry viscosity and yield stress increased with
315
increase in the initial pressure and decrease in temperature (i.e., increasing the hydrate formation rate). High formation rate
316 317 318
Low formation rate
Figure 12. Schematic of the microscopic structure of the hydrate particle-water droplet agglomerations at different formation rates. 240
Normalized Adhesion Force/mN/m
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
H-D-H, 6.0℃ H-D-H, 1.5℃ 8 H-D-W,1.5℃ 8 H-D-W,7.0℃ 16 H-H, 3.2℃
200
160
120
80
40
0
0
50000 100000 150000 200000 250000 300000 350000 400000 2
Contact Area/µm
319 320 321 322 323
Figure 13. Comparisons between the cyclopentane hydrate particle-hydrate particle (H-H),16 hydrate particle-droplet-aluminum plate/wall (H-D-W) 8 and hydrate particle-droplet-hydrate particle (H-D-H) normalized adhesion forces.
324
Extensive experimental and theoretical works have studied the adhesion forces between dry cyclopentane
325
hydrate particle-particle (H-H) and cyclopentane hydrate particle-droplet-wall/plate (H-D-W) interactions.8, 12-17,
326
19-22
327
As shown in Figure 13, compared with the case of dry hydrate particles (~4.3 mN/m at 3.2 °C), the existence of
328
unconverted water droplets significantly increased the adhesion forces between the hydrate particles. The
Herein, the adhesion forces of these two cases were compared with the adhesion forces in this study (H-D-H).
17
ACS Paragon Plus Environment
Energy & Fuels
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 18 of 23
329
adhesion forces were at least an order of magnitude larger and increased as more water converted into hydrate
330
particles. Compared with the hydrate-droplet-aluminum plate interactions, at a smaller extent of subcooling (i.e.,
331
1.7 or 0.7 °C), the hydrate was not visibly converted from the water droplets during both measurements, and the
332
corresponding adhesion forces of these two cases were in good agreement. Notably, if the aluminum plate was
333
replaced with other plate materials, the corresponding adhesion forces might have exhibited significant deviations
334
in this study because the experimental work and theoretical model confirmed that the characteristics of the plate
335
(e.g., wettability) could affect the adhesion force. At a high level of subcooling (i.e., 6.2 °C), the adhesion forces
336
in this work were significantly larger than hydrate particle-water droplet-aluminum plate interactions. This result
337
was attributed to the amount of hydrate formed from the droplet during both measurements at 1.5 °C, for the case
338
of the hydrate-droplet–wall/plate interactions, the hydrate shell growth began from one side (i.e., the interface
339
between the hydrate particle and water bridge) and moved to the other side, while for the measurements in this
340
study, as shown in Figure 7 and 8, the hydrate shell growth began from two sides and moved along the capillary
341
bridge. Hence, more hydrates were formed from the water droplets during the present measurements. According to
342
the experimental and theoretical work, more hydrate formation would lead to larger adhesion forces.8, 24, 29
343
Previous reports and our work suggest that the pendular liquid bridge model can account for hydrate
344
particle-particle or hydrate particle-plate interactions in the presence of a water bridge.7,
345
indicates that the interaction force is proportional to the water-hydrocarbon interfacial tension. Based on this
346
quantitative relation, the adhesion forces of the natural gas hydrates particle in high-pressure systems can be
347
preliminary estimated with the adhesion forces present in this work. The interfacial tension of a
348
water-hydrocarbon system varies from approximately 72 mN/m for water/gas systems to 20 to 50 mN/m for
349
water/oil systems at atmospheric conditions.31-32 With the difference in the interfacial tension from the present
350
pure cyclopentane system (~48.7 mN/m),8 the adhesion forces of natural gas hydrate particles can be determined
351
to be approximately 1.5 times for water/gas systems and 2/5 to 1 as large for water/oil systems compared to those 18
ACS Paragon Plus Environment
24, 29-30
The model
Page 19 of 23
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
352
in this work. Notably, the above preliminary estimations were determined using the water-hydrocarbon interfacial
353
tension at atmospheric conditions. In fact, the pressures and temperatures in realistic pipelines will affect the
354
interfacial tension.31-32 Furthermore, in addition to the interfacial tension, the adhesion forces were also affected
355
by the contact area between the hydrate particle and water droplet, growth rate of the hydrate shell and volume of
356
the droplet.24, 29 Therefore, the accuracy of the preliminary estimations needs to be verified by future natural gas
357
hydrate adhesion force measurement experiments under high pressure.
358 359
CONCLUSIONS
360
In this study, we proposed a novel method to directly measure the interaction between hydrate particles and
361
water droplets. The effects of the temperature, liquid water volume and mineral oil on the interaction behavior
362
were investigated. Unconverted water droplets played a crucial role in the hydrate particle agglomeration process.
363
At a smaller extent of subcooling, as the water droplet volumes increased, the contact areas and adhesion forces
364
between the hydrate particles and water droplets increased moderately, followed by a significant increase. For a
365
higher level of subcooling, a higher hydrate formation rate prevented effective wetting of water on the hydrate
366
particle surface, thereby resulting in smaller contact areas. In addition, no clear relationship existed between the
367
contact area/adhesion force and the water droplet volume. The hydrate formed from the liquid bridge could
368
dramatically strengthen the adhesion force, and the addition of mineral oil retarded the liquid droplets from
369
converting into hydrates, consequently decreasing the adhesion force.
370 371
AUTHOR INFORMATION
372
Corresponding Authors
373
*E-mail:
[email protected] 374
[email protected] 19
ACS Paragon Plus Environment
Energy & Fuels
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
375
Notes
376
The authors declare no competing financial interest
377 378
ACKNOWLEDGEMENTS
379
The authors acknowledge the support from the China Postdoctoral Science Foundation funded projects
380
(Grant No. 2015M580619 and 2016T90659), Shandong Provincial Natural Science Foundation (Grant No.
381
ZR2016EEB04), and Program for Changjiang Scholars and Innovative Research Team in the University (Grant
382
IRT1294). Chenwei Liu also thanks Professor Carolyn A. Koh (Center for Hydrate Research, Colorado School of
383
Mines) for her generous support and guidance on the MMF measurements.
384 385
REFERENCES
386
[1] Sloan, E.D.; Koh, C.A. Clathrate Hydrates of Natural Gases. Third Edition; CRC Press−Taylor & Francis
387 388 389
Group: Boca Raton, FL, 2007. [2] Zhao, J. F.; Zhu, Z. H.; Song, Y. C.; Liu, W. G.; Zhang, Y.; Wang, D.Y. Analyzing the process of gas production for natural gas hydrate using depressurization, Applied Energy 2015, 142, 125–134.
390
[3] Wang, J.Q; Zhao, J.F.; Yang, M.J.; Li, Y.H.; Liu, W.G.; Song, Y.C. Permeability of laboratory-formed porous
391
media containing methane hydrate: Observations using X-ray computed tomography and simulations with
392
pore network models, Fuel 2015, 145, 170-179.
393 394
[4] Turner, D.J. Clathrate Hydrate Formation in Water-in-oil Dispersions. Ph.D. Dissertation, Colorado School of Mines, Golden, CO. 2005.
395
[5] Parikh, D.M. Handbook of Pharmaceutical Granulation Technology. Third Edition, CRC Press, 2009.
396
[6] Dhenge, R. M.; Washino, K.; Cartwright, J.J.; Houslow, M.J.; Salman, A.D. Twin Screw Granulation using
397
Conveying Screws: Effects of Viscosity of Granulation Liquids and Flow of Powders. Powder Technology 20
ACS Paragon Plus Environment
Page 20 of 23
Page 21 of 23
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
398 399 400 401 402 403 404 405 406 407 408 409 410
Energy & Fuels
2013, 238, 77-90. [7] Iveson, S.M.; Lister, J.D.; Hapgood, K.; Ennis, B.J. Nucleation, Growth and Breakage Phenomena in Agitated Wet Granulation Processes: A Review. Powder Technology 2001, 117, 3-39. [8] Liu, C.W.; Li, M.Z.; Zhang, G.D.; Koh, C.A. Direct Measurements of the Interactions between Clathrate Hydrate Particles and Water Droplets. Phys. Chem. Chem. Phys. 2015, 17, 20021-20029. [9] Ennis, B.J.; Litster, J.D. Particle size enlargement, in Perry’s Chemical Engineers’ Handbook, ed. R. Perry and D. Green, McGraw-Hill, New York, 7th edn, 1997. [10] Walsie, B. Growth Mechanism and the Dependence of Granule Size on Drop Size in Fluidized-Bed Granulation. Chemical Engineering Science 1991, 46, 2781-2785. [11] Greaves, D.; Boxall, J.; Mulligan, J.; Sloan, E.D.; Koh, C.A. Hydrate formation from high water content-crude oil emulsions. Chemical Engineering Science 2008. 63, 4570–4579. [12] Yang, S.; Kleehammer, D.M.; Huo, Z.; Sloan, E.D.; Miller, K.T. Micromechanical Measurements of Hydrate Particle Attractive Forces. Journal of Colloid and Interface Science 2004, 277, 335-341.
411
[13] Taylor, C.J.; Dieker, L.E.; Miller, K.T.; Koh, C.A.; Sloan, E.D. Micromechanical Adhesion Force
412
Measurements between Tetrahydrofuran Hydrate Particles. Journal of Colloid and Interface Science 2007,
413
306, 255-261.
414
[14] Dieker, L.E.; Aman, Z.M.; George, N.C.; Sum, A.K.; Sloan, E.D.; Koh, C.A. Micromechanical Adhesion
415
Force Measurements between Hydrate Particles in Hydrocarbon Oils and Their Modifications. Energy &
416
Fuels 2009, 23, 5966-5971.
417
[15] Aman, Z.M.; Dieker, L.E.; Aspenes, G.; Sum, A.K.; Sloan, E.D.; Koh, C.A. Influence of Model Oil with
418
Surfactants and Amphiphilic Polymers on Cyclopentane Hydrate Adhesion Forces. Energy & Fuels 2010, 24,
419
5441-5445.
420
[16] Aman, Z.M.; Brown, E.P.; Sloan, E.D.; Sum, A.K.; Koh, C.A. Interfacial Mechanisms Governing 21
ACS Paragon Plus Environment
Energy & Fuels
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
421
Cyclopentane Clathrate Hydrate Adhesion/Cohesion. Phys. Chem. Chem. Phys. 2011, 13, 19796-19806.
422
[17] Aman, Z.M.; Sloan, E.D.; Sum, A.K.; Koh, C.A. Lowering of Clathrate Hydrate Cohesive Forces by Surface
423 424 425 426 427 428 429 430 431
Active Carboxylic acids. Energy & Fuels 2012, 26, 5102-5108. [18] Davies, S.R. Role of Transport Resistances in the Formation and Remediation of Hydrate Plugs. Ph.D. Thesis, Colorado School of Mines, Golden, CO. 2009. [19] Song, J. H.; Couzis, A.; Lee, J. W. Direct Measurements of Contact Force between Clathrate Hydrate and Water. Langmuir 2010, 26, 9187-9190. [20] Song, J. H.; Couzis, A.; Lee, J. W. Investigation of Microscopic Interfacial Dynamics between Clathrate Hydrates and Surfactant Solutions. Langmuir 2010, 26, 18119-18124. [21] Cha, M.J.; Couzis, A.; Lee, J.W. Macroscopic Investigation of Water Volume Effects on Interfacial Dynamic Behaviors between Clathrate Hydrate and Water. Langmuir 2013, 29, 5793-5800.
432
[22] Aspenes, G.; Dieker, L. E.; Aman, Z. M.; Hoiland, S.; Sum, A. K.; Koh, C. A.; Sloan, E. D. Adhesion Force
433
between Cyclopentane Hydrates and Solid Surface Materials. Journal of Colloid and Interface Science 2010,
434
343, 529-536.
435 436
[23] Fidel-Dufour, A.; Gruy, F.; Herri, J. M. Rheology of Methane Hydrate Slurries during Their Crystallization in a Water in Dodecane Emulsion under Flowing. Chemical Engineering Science 2006, 61, 505-515.
437
[24] Liu, C. W.; Li, M. Z.; Liu, C. T.; Geng, K. L.; Li, Y. X. Micromechanical Interactions between Clathrate
438
Hydrate Particles and Water Droplets: Experiment and Modeling. Energy & Fuels 2016, 30, 6240-6248.
439
[25] Liu, C. W.; Li, M. Z.; Liang, C.; Wang, W. Y. Measurement and Analysis of Bimodal Drop Size Distribution
440
in a Rotor-Stator Homogenizer. Chemical Engineering Science 2013, 102, 622-631.
441
[26] Wessel, R.; Ball, R. C. Fractal aggregates and gels in shear flow. Phys. Rev. A 1992, 46, 3008-3011.
442
[27] Webb, E. B.; Koh, C. A.; Liberatore, M.W. Rheological Properties of Methane Hydrate Slurries Formed from
443
AoT+Water+oil Microemulsions. Langmuir 2013, 29, 10997-11004. 22
ACS Paragon Plus Environment
Page 22 of 23
Page 23 of 23
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
444
[28] Webb, E. B.; Rensing, P. J.; Koh, C. A.; Sloan, E. D.; Sum, A. K.; Liberatore, M. W. High Pressure
445
Rheometer for in Situ Formation and Characterization of Methane Hydrates. Energy & Fuels 2012, 26,
446
3504-3509.
447
[29] Liu, C. W.; Li, Y. X.; Wang, W. Y.; Dong, S. B.; Li, M. Z. Modeling the micromechanical interactions
448
between clathrate hydrate particles and water droplets with reducing liquid volume. Chemical Engineering
449
Science 2017, 163, 44-55.
450
[30] Pepin, X.; Rossetti, D.; Iveson, S. M.; Simons, S. J. R. Modeling the evolution and rupture of pendular liquid
451
bridges in the presence of large wetting hysteresis. Journal of Colloid and Interface Science 2000, 232, 289–
452
297.
453 454 455
[31] Firoozabadi, A.; Ramey, H. Y. J. Surface tension of water-hydrocarbon systems at reservoir conditions. Journal of Canadian Petroleum Technology 1988, 27, 41-48. [32] Ramey, H.Y. J. Correlations of surface and interfacial tensions of reservoir fluids. SPE-4429-MS 1973.
456
23
ACS Paragon Plus Environment
