甲烷水合物在无柄水滴上的结晶
Summary
我们描述了一种在无柄水滴上形成气体水合物的方法，以研究各种抑制剂，启动子和底物对水合物晶体形态的影响。
Abstract
本文描述了一种在水滴上形成甲烷水合物壳的方法。此外，它还提供了额定工作压力为10 MPa的压力传感器的蓝图，其中包含用于无柄液滴的阶段，用于可视化的蓝宝石窗口以及温度和压力传感器。连接到甲烷气瓶的压力泵用于将电池加压至5 MPa。冷却系统是一个10加仑（37.85升）的罐，含有50%的乙醇溶液，通过乙二醇通过铜盘管冷却。这种设置可以分别观察与冷却和减压期间与水合物形成和解离相关的温度变化，以及液滴形态变化的可视化和摄影。使用该方法，在~-6°C至-9°C下观察到水合物壳的快速形成。 在减压过程中，由于放热水合物解离，在压力/温度（P / T）稳定性曲线下观察到0.2°C至0.5°C的温度下降，通过在温度下降开始时的熔化视觉观察证实。在从2 MPa抑制到5 MPa后观察到”记忆效应”。这种实验设计允许监测液滴随时间推移的压力，温度和形态，使其成为测试水合物形态上的各种添加剂和底物的合适方法。
Introduction
天然气水合物是氢键水分子的笼子， 通过 范德华相互作用捕获客体气体分子。甲烷水合物在高压和低温条件下形成，这些条件发生在自然界中沿大陆边缘的地下沉积物中，北极永久冻土层下以及太阳系中的其他行星体1。天然气水合物储存了数千亿吨碳，对气候和能源具有重要意义2。天然气水合物在天然气工业中也可能是危险的，因为天然气管道中会出现有利于水合物的条件，这可能会堵塞管道，导致致命的爆炸和石油泄漏3。
由于原位研究天然气水合物的困难，实验室实验通常用于表征水合物的性质以及抑制剂和底物的影响4。这些实验室实验是通过在各种形状和大小的细胞中以高压生长气体水合物来进行的。防止天然气管道中天然气水合物形成的努力导致了几种化学和生物天然气水合物抑制剂的发现，包括防冻蛋白（AFP），表面活性剂，氨基酸和聚乙烯吡咯烷酮（PVP）5，6。为了确定这些化合物对天然气水合物性质的影响，这些实验采用了不同的容器设计，包括高压灭菌器，结晶器，搅拌反应器和摇摆池，其支持0.2至106立方厘米4的体积。
这里和以前的研究7，8，9，10，11，12中使用的无柄液滴方法涉及在压力池内的无柄水滴上形成气体水合物膜。 这些容器由不锈钢和蓝宝石制成，可承受高达10-20 MPa的压力。电池连接到甲烷气瓶。其中两项研究使用液滴方法测试AFPs作为气体水合物抑制剂与商业动能水合物抑制剂（KHI）相比，如PVP7，11。Bruusgard等人7专注于抑制剂的形态学影响，发现含有I型AFPs的液滴在高驱动力下具有比没有抑制剂的树突状液滴表面更光滑的玻璃状表面。
Udegbunam等人11使用在先前研究10中开发的评估KHI的方法，该方法允许分析形态/生长机制，水合物 – 液体 – 蒸汽平衡温度/压力以及动力学作为温度的函数。Jung等人研究了CH 4 -CO2在形成CH4水合物壳8后用CO2淹没细胞的替代物。Chen等人观察到奥斯特瓦尔德成熟，水合物壳形成9。Espinoza等人研究了各种矿物基质上的CO2水合物壳12。液滴法是一种相对简单和廉价的方法，用于确定各种化合物和底物对天然气水合物的形态效应，并且由于体积小而需要少量添加剂。本文描述了一种使用不锈钢电池在水滴上形成这种水合物壳的方法，该电池具有蓝宝石窗口进行可视化，额定工作压力高达10 MPa。
Protocol
1. 设计、验证和加工压力池。 设计细胞以允许直接可视化水滴形成的水合物。确保电池具有带透明蓝宝石窗口的主腔室和四个用于流体/气体入口、出口、灯和电线的端口（图1）。在工程设计软件中创建最终设计（附图S1）。 要检查压力池在工作高压下是否安全，请使用仿真软件进行有限元分析。 将工程设计软件中的全尺寸压力单元模型输…
Representative Results
使用这种方法，可以通过压力池的蓝宝石窗口以及温度和压力传感器直观地监测液滴上的气体水合物壳。为了在加压至5 MPa后使水合物壳成核，可以将干冰添加到压力池的顶部以诱导热冲击以触发快速水合物结晶。干冰强制水合物壳形成时存在明显的形态差异。水滴从光滑的反射表面（图3A）过渡到具有轻微树突表面的不透明水合物壳（图3B）。添加100?…
Discussion
我们开发了一种在无柄水滴上安全地形成甲烷水合物壳的方法，并将该方法共享到额定工作压力为10 MPa的压力池以及加压和冷却系统。压力传感器配有一个包含嵌入式热电偶的液滴台，一个用于可视化液滴的蓝宝石窗口，以及一个固定在电池顶部的压力传感器。冷却系统包括冷却的乙二醇，通过带有50%乙醇溶液的罐中的铜线圈循环，其中放置了压力池。压力泵将气体从气缸加压到压力池。水合物?…
Declarações
The authors have nothing to disclose.
Acknowledgements
NASA外星生物学拨款80NSSC19K0477资助了这项研究。我们感谢威廉·韦特和尼古拉斯·埃斯皮诺萨的宝贵讨论。
Materials
| CAMERA AND LAPTOP | |||
| Camera Body | Nikon | D7200 | Name in Protocol: camera |
| Camera Control Pro 2 Software | Nikon | Name in Protocol: camera software | |
| Laptop | HP Pavilion | hp-pavilion-laptop-14-ce0068st | Needs to be PC with plenty of storage (~ 1 Tb) Name in Protocol: laptop |
| Macrophotography Lens | Nikon | AF-S MICRO 105mm f/2.8G IF-ED Lens | Name in Protocol: lens |
| CONSUMABLES | |||
| Deionized water | Name in Protocol: DI water | ||
| Dry Ice | VWR or grocery store | Buy just before nucleation Name in Protocol: dry ice |
|
| Ethanol | Name in Protocol: ethanol | ||
| Ethylene Glycol | Name in Protocol: ethylene glycol | ||
| COOLING SYSTEM | |||
| 1/2 in. O.D. x 3/8 in. I.D. x 25 ft. Polyethylene Tubing | Everbilt | Model # 301844 | For circulating coolant from chiller to copper coils in aquarium Name in Protocol: 3/8” (inner diameter) plastic tubing |
| Circulating chiller | Polyscience | Name in Protocol: chiller | |
| Economical Flexible Polyethylene Foam Pipe Insulation | McMaster-Carr | 4530K162 | 3/4" thick wall; 1/2" inner diameter; R Value 3; 6' long Name in Protocol: foam pipe insulation |
| Plastic tubing | use any tubing that fits the airline connection in the lab and long enough to travel from the airline connection to the front of the aquarium | ||
| DATALOGGER | |||
| Armature Multiplexer Module for 34970A/ 34972A, 20-Channel |
Keysight Technologies | 34901A | Name in Protocol: datalogger multichannel |
| Benchvue or Benchlink software | Benchvue or Benchlink | Name in Protocol: temperature transducer software | |
| Data Acquisition/Switch Unit. GPIB, RS232 | Keysight Technologies | 34970A | Name in Protocol: datalogger |
| USB/GPIB interface | Keysight Technologies | 82357B | Name in Protocol: datalogger USB |
| datalogger multichannel | |||
| Schott Fostec -Llc 20510 Ace Fiber Optic Light Source | Schott Fostec | A20500 | 3115PS-12W-B20 115 V ~AC 50/60Hz 5/4.5 W Name in Protocol: light source unit |
| Schott Fostec light source guide – single bundle | Schott Fostec | A08031.40 | Name in Protocol: fiber optic light source cable |
| METHANE GAS AND REGULATOR | |||
| 1/4 OD in. x 20 ft. Copper Soft Refrigeration Coil | Everbilt | Model # D 04020PS | For pressurizing ISCO pressure pump. An additional pack is needed for coolant circulation, as listed below. Name in Protocol: high pressure-rated 1/4” copper pipe |
| Methane cylinder regulator | Airgas | Y11N114G350-AG | Name in Protocol: methane cylinder regulator |
| Methane gas cylinder | Airgas | ME UHP300 | Name in Protocol: methane gas cylinder |
| PRESSURE PUMP | |||
| 1/4 in. flexible tubing, ~ 3 ft. | Connect to pump inlet for leak test Name in Protocol: 1/4" flexible tubing |
||
| 260D Syringe Pump W/Controller | Teledyne Instruments Inc. | 67-1240-520 | Name in Protocol: pressure pump |
| Controller − Ethernet/USB | Teledyne Instruments Inc. | 62-1240-114 | Purchase if you would like to install Labview onto computer and control pressure pump remotely. We did not do this. |
| Smooth-Bore Seamless 316 Stainless Steel Tubing, 1/4" OD, 0.035" Wall Thickness, 1 Foot Long (x5) | McMaster-Carr | 89785K824 | Name in Protocol: 1/4" pipe |
| Smooth-Bore Seamless 316 Stainless Steel Tubing, 1/8" OD, 0.02" Wall Thickness, 1 Foot Long (x4) | McMaster-Carr | 89785K811 | Name in Protocol: 1/8" pipe |
| Stainless Steel Swagelok Tube Fitting, Reducing Union, 1/4 in. x 1/8 in. Tube OD (x4) | Swagelok | SS-400-6-2 | Name in Protocol: 1/8” to 1/4” adapter |
| PRESSURE CELL | |||
| 316 Stainless Steel Nut and Ferrule Set (1 Nut/1 Front Ferrule/1 Back Ferrule) for 1/4 in. Tube Fitting (20) | Swagelok | SS-400-NFSET | Used for fitting connections where necessary Name in Protocol: ferrule set |
| 316L Stainless Steel Convoluted (FM) Hose, 1/4 in., 316L Stainless Steel Braid, 1/4 in. Tube Adapters, 60 in. (1.5 m) Length | Swagelok | SS-FM4TA4TA4-60 | Connects pressure pump to pressure cell Name in Protocol: 1/4" braided stainless steel flexible pressure-rated hose |
| ABAQUS | ABAQUS FEA | Name in Protocol: simulation software | |
| Abrasion-Resistant Cushioning Washer for 7/8" Screw Size, 0.875" ID, 2.25" OD, packs of 10 (x1) | McMaster-Carr | 90131A107 | Name in Protocol: 2.25" rubber washer |
| Abrasion-Resistant Sealing Washer, Aramid Fabric/Buna-N Rubber, 3/8" Screw Size, 0.625" OD, packs of 10 (x1) | McMaster-Carr | 93303A105 | Used for illumination port |
| Acrylic Sheet | White 2447 / WRT31 Extruded Paper-Masked (Translucent 55% (0.118 x 12 x 12) |
Interstate Plastics | ACRW7EPSH | Machine a circle of acrylic to fit in the inner chamber of the pressure cell to serve as the background for imaging Name in Protocol: acrylic disc |
| AutoCAD | AutoCAD | Name in Protocol: engineering design software | |
| Conax fitting | Conax Technologies | 311401-011 | TG(PTM2/)-24-A6-T, OPTIONAL 1/4" NPT Name in Protocol: pressure seal connector |
| High Accuracy Oil Filled Pressure Transducers/Transmitters for General industrial applications (x2) |
Omega Engineering, Inc. | PX409-3.5KGUSBH | Buy two so there is a backup. Name in Protocol: pressure transducer |
| HIGH PRESSURE CHAMBER PARTS | Wither Tool, Die and Manufacturing Company | Machining for pressure cell parts as listed in CAD drawings (Figure S1) Name in Protocol: Part B = stainless steel washer |
|
| High-Strength 316 Stainless Steel Socket Head Screw, M5 x 0.80 mm Thread, 14 mm Long (x20) | McMaster-Carr | 90037A119 | Used for illumination port |
| High-Strength 316 Stainless Steel Socket Head Screw, M8 x 1.25 mm Thread, 25 mm Long (x20) | McMaster-Carr | 90037A133 | Name in Protocol: M8 stainless steel screws |
| Oil-Resistant Hard Buna-N O-Ring, 3/32 Fractional Width, Dash Number 120, packs of 50 (x1) | McMaster-Carr | 5308T178 | Name in Protocol: 1" o-ring |
| Oil-Resistant Hard Buna-N O-Ring, 3/32 Fractional Width, Dash Number 128, packs of 50 (x1) | McMaster-Carr | 5308T186 | Name in Protocol: 1.5" o-ring |
| Omega Inc. pressure transducer software | Omega Engineering, Inc. | Name in Protocol: pressure transducer software | |
| Polycarbonate Disc | McMaster-Carr | 8571K31 | Listed in CAD drawings for illumination port, Fig. S1 Part E |
| Sapphire windows (x3) | Guild Optical Associates, Inc. | Optical Grade Sapphire Window, C-Plane Diameter: 1.811” ±.005” Thickness: .590” ±.005” Surface Quality: 60/40 Edges ground and safety chamfered |
Buy three so there are two backups. Name in Protocol: sapphire window |
| Solid Thermocouple Wire FEP Insulation and Jacket, Type K, 24 Gauge, 50 ft. Length (x1) | McMaster-Carr | 3870K32 | Name in Protocol: thermocouples |
| Stainless Steel Integral Bonnet Needle Valve, 0.37 Cv, 1/4 in. Swagelok Tube Fitting, Regulating Stem (x4) | Swagelok | SS-1RS4 | Two will be used for the pressure pump as well. Name in Protocol: 1/4" needle valves |
| Stainless Steel Pipe Fitting, Hex Nipple, 1/4 in. Male NPT (x2) | Swagelok | SS-4-HN | Used for illumination port |
| Stainless Steel Swagelok Tube Fitting, Female Branch Tee, 1/4 in. Tube OD x 1/4 in. Tube OD x 1/4 in. Female NPT (x2) | Swagelok | SS-400-3-4TTF | Used with pressure transducer Name in Protocol: branch tee fitting |
| Stainless Steel Swagelok Tube Fitting, Male Connector, 1/4 in. Tube OD x 1/4 in. Male NPT (x4) | Swagelok | SS-400-1-4 | Used on top port and side port leading to needle valves Name in Protocol: NPT screws |
| Stainless Steel Swagelok Tube Fitting, Port Connector, 1/4 in. Tube OD (x8) | Swagelok | SS-401-PC | Use as tube connections between NTP and valve connections Name in Protocol: port connector fitting |
| TANK | |||
| 1/4 OD in. x 20 ft. Copper Soft Refrigeration Coil | Everbilt | Model # D 04020PS | For circulating coolant Name in Protocol: 1/4" copper pipe |
| 10 gallon aquarium | Tetra | Name in Protocol: 10 gallon tank | |
| 2 oz. Waterweld | J-B Weld | Model # 8277 | Name in Protocol: underwater sealant |
| 3 in. x 25 ft. Foil Backed Fiberglass Pipe Wrap Insulation | Frost King | Model # SP42X/16 | For wrapping around aquarium Name in Protocol: foil-lined fiberglass |
| 3/8 7/8 in. Stainless Steel Hose Clamp (10 pack) | Everbilt | Model # 670655E | Name in Protocol: worm drive hose clamps |
| Styrofoam | Name in Protocol: insulating material | ||
| TOOLS | |||
| 1-1/8 in. Ratcheting Tube Cutter | Husky | Model # 86-036-0111 | |
| 1/2 in. to 1 in. Pipe Cutter | Apollo | Model # 69PTKC001 | |
| Adjustable wrench (x2) | Steel Core | Model # 31899 | Need two wrenches with jaw at least 1" |
| Allen wrench set | Home Depot | ||
| Duct tape | Name in Protocol: duct tape | ||
| Flexible tubing, like an IV line, to fit on the end of grainger probe (canula) | Name in Protocol: IV tube | ||
| Grainger 18 gauge probe | Grainger | For inserting droplet Name in Protocol: cannula |
|
| High Vacuum Grease | Dow corning | Apply to o-rings before inserting sapphire window Name in Protocol: vacuum grease |
|
| Klein Tools Professional 90 Degree 4-in-1 Tube Bender | Klein Tools | Model # 89030 | Name in Protocol: tube bender |
| Snoop liquid leak detector | Swagelok | MS-SNOOP-8OZ | To detect leaks when pressurized when methane Name in Protocol: liquid leak detector |
| Suction cup | Home Depot | For removing tight fitting sapphire window Name in Protocol: suction cup |
|
| Teflon Tape | Name in Protocol: plumber's tape | ||
| Temflex 3/4 in. x 60 ft. 1700 Electrical Tape Black | 3M | Model # 1700-1PK-BB40 | Name in Protocol: electrical tape |
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- Udegbunam, L. U., DuQuesnay, J. R., Osorio, L., Walker, V. K., Beltran, J. G. Phase equilibria, kinetics and morphology of methane hydrate inhibited by antifreeze proteins: application of a novel 3-in-1 method. The Journal of Chemical Thermodynamics. 117, 155-163 (2018).
- Espinoza, D. N., Santamarina, J. C. Water-CO2-mineral systems: Interfacial tension, contact angle, and diffusion – Implications to CO2 geological storage. Water Resources Research. 46 (7537), 1-10 (2010).
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Citar este artigo
Johnson, A. M., Zhao, Y., Kim, J., Dai, S., Glass, J. B. Methane Hydrate Crystallization on Sessile Water Droplets. J. Vis. Exp. (171), e62686, doi:10.3791/62686 (2021).