The Center for Hydrate Research is equipped with a number of apparatuses and instruments for the study of hydrates formation, dissociation, kinetics, structure, morphology, rheology, and modeling. Besides the analytical instrumentation, the Center has several custom made cells (low and high pressure) for the study of hydrates. For lab tour videos and poster presentaions, please see the Koh recruiting page.

Rocking Cells

Rocking-cells Facilities

A rocking cell constitutes a metallic structure encapsulating two sapphire tubes that allow to visually assess the hydrate slurry formed. Cells rock back and forth to promote mixing of their content. A metal ball is used to disturb the interface between oil, gas and water, and facilitates the breakage of hydrate agglomerates. Pressure of each cell and thermal bath temperature are tracked over time to determine the hydrate onset formation and kinetic of water conversion. Rocking cells are mainly used to evaluate commercial and natural hydrate anti-agglomerants (AAs).


Microfluidics Facilities

The microfluidic device is primarily used to measure phase equilibrium properties of gas systems, most recently CO2-H2O and MeOH-H2O-CH4. It is used in conjunction with Raman Spectroscopy and GC-MS to obtain phase measurement and phase composition, respectively.

The microfluidic chip has a serpentine channel design that has been sandblasted into borosilicate glass, with channel dimension of 200 x 200 µm. There are three inlet ports, which allow for three different fluids to be flowed into the device via syringe pumps. The temperature is controlled by a thermoelectric cooler, capable of temperatures ranging from -30°C to 45°C. The maximum operating pressure is 1500 psi, which is maintained and controlled by a back pressure regulator. The outlet of the microfluidic chip is currently analyzed by Gas Chromatography Mass Spectrometry to determine the chemical composition of the gas phase. Raman Spectroscopy can also be used to measure the phases present in the microchannels, since the chip is made of glass. This system increases greatly increases the experimental throughput of thermodynamic phase equilibria measurements. It is also possible to measure hydrate kinetics using a very similar chip design and experimental procedure.

Jamming Flume

flume_jam Facilities

The Center has recently started studies to understand hydrate jamming phenomena in flow channels. This project tackles the jamming problem with both experimental and modeling efforts. In the experimental side, an open flume was build to investigate jamming of model particles (polyethylene disks). This is our first attempt at quantifying the most important variables associated with jamming which can be later developed to understand jamming of hydrate particles. In the modeling side, 2-D simulations are being performed for equivalent systems being tested experimentally. The combination of these two components represents another important step toward building a better and more robust model to predict hydrate formation and plugability in pipelines.

TA Instruments AR-G2 Rheometer

Rheometer_ARG2 Facilities

To investigate clathrate hydrate slurries a commercial TA Instruments AR-G2 rheometer equipped with a pressure cell is utilized. The pressure cell is a constant volume cell with a concentric cylinder geometry (cup radius 14 mm and bob radius of 13 mm) capable of operating at pressures of up to 13.8 MPa. The pressure cell is also equipped with a Peltier cooler with a temperature range from -10 to 150° C. 

The AR-G2 is a controlled stress rheometer capable of conducting dynamic or steady shear tests over time. The dynamic oscillation tests can be preformed at a frequency range from 7.5×10−7 to 628 rad/s. The shear tests can be run with an angular rotation 1.4×10−19 to 300 rad/s with torque sensitivity from 0.003 μN/m up to 200 mN/m. However, when the pressure cell is attached the sensitivity drops to approximately 100 μN/m.

Shear and oscillatory time sweeps experiments are possible with this rheometer. Shear time sweeps are conducted by running the rheometer at a constant shear rate (or speed). During the entire test torque measurements are recorded (every 10 seconds) and are report as effective viscosities. These measurements are used to detect clathrate hydrate nucleation and changes in the sample over time as it was sheared. Shear ramps are conducted by starting at a low shear rate and increasing the shear rate. Again torque measurements are recorded and reported as effective viscosities. These shear ramps are done on a much shorter time scale than the time sweeps, helping to eliminate convoluting effects. From these measurements information such as shear thinning can measured and yield stresses can be estimated. For oscillatory time sweeps, the rheometer is oscillated at a constant frequency and constant strain. The torque responses are measured over time, reported as the elastic (G’) and loss moduli (G”). These tests are used to detect clathrate hydrate nucleation and changes in the sample over time, while under relatively quiescent conditions.

High Pressure Flowloop

Flowloop Facilities

The CHR high-pressure deposition flowloop consists of a 38 ft long, 2 inch nominal diameter stainless steel multiphase flowline feeding into a gas/liquid separator, where the gas can be recirculated to the beginning of the flowline by passing through a blower and the liquids are recirculated to the beginning of the flowline by a centrifugal pump. The separator is actively cooled via direct contact of process fluids with coolant filled copper coils. Four actively cooled sections of the multiphase flow line allow for temperature control in the flowloop, and two of these sections are equipped with Rosemount 3051 systems to monitor the differential pressure across the sections. One of those sections is equipped with two clear viewing windows, allowing for visual observation of the flow and any hydrate phenomena occurring. Process fluid pressures and temperatures are measured at various points throughout the loop, and a flow rate and density meter (Micromotion F100S) gathers data on the flow rate and density of liquids being discharged by the centrifugal pump. The system allows for the formation of hydrate deposits in-situ.

High Pressure Water tunnel

Picture1 Facilities

The high-pressure water tunnel (HPWT) consists of 16ft of pipe and can withstand up to 3000 psi and near freezing temperatures. The testing section contains a visual window where hydrate nucelation on gas bubbles can be studied in the ~0.4 ft/s countercurrent flow. A high-speed/high-resolution camera is used to capture images/videos suspended gas bubbles.

High Pressure Micro DSC VIIa

dsc1 Facilities

The Micro DSC VIIa was installed in June of 2005. This instrument is used primarily to study gas hydrate phase equilibrium, kinetics, and thermal properties. The DSC can achieve temperatures of -45ºC to 120ºC which allows for a broad range of measurements. The low temperatures do not require outside cooling as the system use a Peltier device for cooling at the lower temperatures. The temperatures can be held constant or can also be placed in scanning mode over a range of temperatures. The calorimetric box also completely surrounds the cells so that sensitive changes in the experiment can be measured.

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dsc2 FacilitiesThe DSC is also coupled with a high pressure panel that allows for a maximum pressure of 400 bar. The cells used for the high pressure panel can hold 0.5 cc of material compared to 1.0 cc for the atmospheric pressure cells. The panel uses a single stage compression unit to compress the gases to the desired pressure. The panel also can be used to introduce binary gases into the DSC for measurements. This is accomplished by using the gas densities and the double inlets on the panel to mix certain compositions of gases.

Currently, the DSC and high pressure panel are being used to investigate the thermal properties of methane hydrates (heat capacity and heat of dissociation) at different temperature ranges and varying pressures. Also, the effect of temperature, pressure, and binary gases on agglomeration of hydrate particles is being analyzed for a shut-in type scenario sense no mixing is incorporated into the DSC cells. Anti-agglomerates will also be used to measure their factors on hydrate formation and dissociation.

Raman Spectrometers

raman Facilities

The Center has one  Raman spectrometer, a Horiba Jobin Yvon LabRAM High Resolution Raman Microscope. It utilizes a 532 nm diode laser or a 632 nm He-Ne laser as an excitation source. Scattered light is collected in a back-scatter geometry and dispersed off of an 1800 grooves/mm or 2400 grooves/mm grating over an 800 mm focal length. The entrance slit is set typically set at 50 µm, but varied between experiments depending on the level of resolution required. Typical spectral resolution ranges from 0.5 to 0.9 cm-1.

The Raman spectra are analyzed using the GRAMS/32® software from Galactic Industries Corporation. The cell used is custom-designed and fabricated by Sam Colgate. The cell is a high-pressure, variable temperature 1 cm3 cell with sapphire windows, with a pressure range up to 70 MPa. The viewing area is 200 mm2. The cell is jacketed, and the temperature is controlled by circulating coolant water.

Contact Angle Apparatus

Contact-Angle Facilities

The contact angle aparatus provides a way to study the interface between hydrates and water droplets in a liquid hydrocarbon phase to quantify its wettability. The apparatus consists of an Olympus IX71 microscope witha movable stage and an Olympus LC35 camera. The microscope and camera can operate at low temperatures and atmospheric pressure to study Cyclopentane or THF hydrates. 

Gas Chromatography

GCMS Facilities

CHR has two gas chromatography systems from Agilent Technologies. These are also couple with mass spectrometers, which allow for compositional measurements of fluid phases.

One of the gas chromatography mass spectrometry (GM-MS) setups includes a 5975C inert XL mass selective detector and a 7890A GC system, and the other setup includes a 5973N mass selective detector and a 6890N Network GC system, all from Agilent Technologies. Both GC-MS systems are coupled with MSD ChemStation software for analysis of the resulting chromatograms. Recently, these GC-MS systems have been used to perform phase equilibria measurements with microfluidics and rocking cell. GC-Ms has also been used to assess the application of hydrates for gas separation.  

CAM 200 Interfacial Tensiometer

ift2 Facilities

Interfacial tension is an important property for predicting interparticle adhesion forces and droplet size distributions in oil and water emulsions. The Center for Hydrate Research has recently acquired an interfacial tensiometer and a densitometer which together can be used to determine this property.

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ift3 Facilities

DMA 4500 from Anton Paar.

The CAM 200 from KSV Instruments is designed for the dynamic measurement of surface and interfacial tensions, static and dynamic contact angles and solid surface free energies. Interfacial tension measurements are made using the pendant drop technique where a Young-Laplace force balance is regressed to the droplet curvature.

A critical component of the force balance is the density difference between the two liquid phases. Density can be measured using the DMA 4500 from Anton Paar. The density is measured using an oscillating U-tube where the frequency of oscillation is used to determine the density of the sample.

High Pressure Autoclave with FBRM and PVM

pvmfbrm1 Facilities

The PVM-FBRM experimental apparatus consists of two particle size analyzer probes in a high pressure cell (up to 1200 psi) that has an internal diameter of 4 inches and a height of 9-10 inches (depending on whether a false bottom is inserted). The cell is mixed via a 6-blade Rushton type flat blade impeller. Temperature, pressure and continuous phase conductivity are all measured inside the cell.

Micro-Mechanical Force Apparatus

micro1 Facilities

The micro-mechanical force apparatus was designed by Dr. K. T. Miller in 2002, and brought over to the laboratory from the Colorado School of Mines Material Science department in 2004. The micro-mechanical testing apparatus was developed to measure the adhesive forces acting between hydrate particles submerged in a cooled liquid.

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As shown in the figure, an inverted light microscope (Carl Zeiss Axiovert S100) is positioned on a vibration isolation table. A cooling cell is attached to the microscope stage, in which hydrates are submerged in a cooled liquid. Two micro-manipulators are connected to the microscope to control the movement of the hydrate particles. One manipulator is a relatively low precision hand-operated micro-manipulator (Narishige MN-151) which is held stationary during the experiment. A second, high precision remote-operated micro-manipulator (Eppendorf Patchman 5173) is used to move one of the hydrate particles.

Digital video microscopy is used to track the movement of particles attached to low spring constant cantilever beams, as the beams are displaced with the moving micro-manipulator. The cantilever beams are made of thin glass fibers (~30 µm diameter) and are attached to the inside of the capillary tubes by epoxy cement. The capillary tubes are held in place by cantilever holders attached to the micro-manipulators. The micro-mechanical force measurement technique is illustrated schematically in the figure below. Hydrate particles are formed on the end of thin glass fiber cantilever beams, which act as springs. Using the micro-manipulators, the hydrate particles are brought into contact (A). Using the remote operated manipulator, a preload contact force of ~10 µN is applied to the hydrates particles and held stationary for multiple seconds (B). The particles are then gently pulled apart from each other using the remote operated manipulator. While the particles are being pulled apart, the stationary cantilever bends due to the particle-particle adhesion (C). At some critical displacement, the adhesive bond between the particles breaks, and the particles separate (D). This displacement of the particles is tracked using digital video microscopy and image analysis. For each adhesion force measurement, the particles are pulled apart 40 times to obtain a range of forces.

micro2 Facilities

13C Magic-Angle Spinning Nuclear Magnetic Resonance

nmr Facilities

Clathrate hydrates crystallize into different structures as function of the guest molecule. Some properties of these compounds, as well as their stability and kinetic behavior are function of the hydrate structure present. 13C magic-angle spinning (MAS) NMR spectra obtained as a function of time permit not only the assignment of the hydrate structure, but also to determine the quantitative distribution of the gas guests in the different cavities of the hydrate structure during dissociation. At the Center for Hydrate Research, 13C MAS NMR spectroscopy is used to provide molecular-scale experimental information on the formation and dissociation mechanisms of the gas hydrates.

All 13C MAS NMR spectra are acquired with a Chemagnetics CMX Infinity 400 NMR spectrometer operating at a frequency of 100.5 MHz for 13C. Proton decoupling fields of 50 kHz and MAS speeds of about 3 kHz are used.