Name: in situ visualization of the phase behavior of oil samples under refinery process conditions
Uploaded: 2017-02-21T15:00:00.000+00:00
Duration: 11 min 20 s
Description: Watch this Scientific Journal Video about In Situ Visualization of the Phase Behavior of Oil Samples Under Refinery Process Conditions at JoVE.com

The authors acknowledge Daniel Palys for supplying Figure 12 and for his assistance in managing laboratory supplies.

Caution: Use all appropriate safety practices when performing an experiment under high temperature and pressure conditions, including the use of engineering controls (H2 flow limiter, pressure regulators, and rupture disc assembly) and personal protective equipment (safety glasses, temperature-resistant gloves, lab coat, full-length pants, and closed-toe shoes). Consult all relevant material safety data sheets (MSDS) before use. Carry out micro-reactor loading and clean-up in a fume hood, as these steps involve the use of harmful volatile organic solvents (toluene and dichloromethane).
NOTE: Setup description (see supplemental file).
1. Micro-reactor Loading
<ol>
	<li>Clamp the micro-reactor vertically and upside-down, with the bottom face-seal (thus positioned at the top) open. 
	NOTE: At this stage, the sapphire window, the custom-machined magnet, the 1/16&#34; ferrule, the brass pad, and the bottom nut should not be assembled yet.
	<ol>
		<li>Ensure that the fittings that are used to connect the micro-reactor to the gas lines are closed.</li>
	</ol>
	</li>
	<li>Load around 0.6 g of sample into the reactor through the open face-seal using a thin spatula.
	<ol>
		<li>If the sample is originally kept in a large container, make a sub-sample before loading the micro-reactor.</li>
		<li>To estimate the amount of sample loaded inside the reactor, weigh the container and the spatula before and after loading, and calculate the mass difference.</li>
	</ol>
	</li>
	<li>Slide the custom-machined magnet onto the thermocouple.</li>
	<li>Slide the 1/16&#34; front ferrule so that the larger circle is facing up.</li>
	<li>Ensure that the sealing surface (i.e., the fitting groove where the sealing ring sits) of the bottom face-seal fitting is clean and dry. 
	NOTE: Given the highly viscous nature of most heavy oil samples, it is very likely that the sealing surface got accidently smeared by the sample during the loading process.
	<ol>
		<li>Dip the tip of a cotton swab in toluene and apply it to the sealing surfaces to clean them. Be careful not to drip toluene inside the reactor cavity, which would contaminate the sample.</li>
		<li>If cleaning with toluene is required, make sure the sealing surfaces are dry before proceeding to the next step.</li>
	</ol>
	</li>
	<li>Ensure that the sapphire window is clean and dry.
	<ol>
		<li>If the sapphire window is dirty, use a cotton swab soaked in a suitable solvent, and then perform a final wash using acetone to clean the window surfaces; let it air dry.</li>
	</ol>
	</li>
	<li>Place the sealing ring on the sealing surface, then the sapphire window on the top of the sealing ring, and then the brass pad on the top of the sapphire window; it is preferable to apply tiny, pinhead-sized drops of lubricant on the brass pad.</li>
	<li>Thread the bottom nut on the bottom face-seal fitting while encapsulating the brass pad and the sapphire window. Adjust the bottom nut until it reaches finger-tight position.</li>
	<li>While holding the reactor upside-down, transfer it to a vice. Use a wrench to tighten the bottom nut by 90&#176; from finger-tight position. 
	NOTE: After this step, the reactor does not need to be held upside-down any longer.</li>
	<li>Check the micro-reactor for potential defects in the seal. 
	NOTE: The window may show some chips or cracks, or a faulty seal can be identified if the compressed surface of the seal on the window does not make a continuous circle.
	<ol>
		<li>In case of a defect, open the micro-reactor for inspection.</li>
		<li>After taking remedying action, use a brand-new sealing ring when attempting to reseal the reactor.</li>
	</ol>
	</li>
</ol>
2. Micro-reactor Installation
<ol>
	<li>Once the micro-reactor is loaded and sealed, connect the reactor to the gas lines and perform tests for leaks.
	<ol>
		<li>Always begin leak testing by using N2 at a maximum pressure of 5 MPa. 
		NOTE: The preferred method for leak testing is the pressure-decay test, where the setup is pressurized and then isolated from the cylinder (closing valves V2 and V3). If the pressure remains stable for an extended amount of time (more than 30 min), no leak is observed.</li>
		<li>Carry out additional leak tests at higher pressures if the target pressure for the upcoming experiment is higher than 5 MPa. 
		NOTE: These additional leak tests can be performed with maximum pressure increments of 6 MPa until the desired pressure condition for the experiment is matched. Consider 16 MPa as the upper limit of pressure for both leak testing and setup operation. 
		NOTE: If the gas used to pressurize the setup in the upcoming experiment is not inert (such as flammable gases), carry out another series of leak tests using the target gas contingent on a successful series of leak tests with N2.</li>
	</ol>
	</li>
	<li>After successful leak tests, depressurize the setup before undertaking the next installation steps.</li>
	<li>Place the micro-reactor in the stainless steel heating block, which is itself inserted in the coil heater. Position the assembly on the platform located above the microscope objective.</li>
	<li>Encase the reactor, the heater, and the heating block with the two halves of a casing filled with ceramic wool. Clamp the two halves of the casing together using a hose clip.</li>
	<li>Fine-tune the position of the reactor over the microscope objective.
	<ol>
		<li>Turn the microscope on using cross-polarized light. Adjust the vertical position of the objective using the lowest magnification so as to focus on the inside surface of the sapphire window.</li>
		<li>Position the reactor so that the field of view at the lowest magnification (typically 50X) covers a radial portion of the window surface where the inner boundary comprises the edge of the 1/16&#34; front ferrule, as described in Figure 1. 
		NOTE: Actual micrographs acquired by the software should be centered subsets of this field of view, which would avoid showing the ferrule itself.</li>
	</ol>
	</li>
	<li>Connect the thermocouple of the micro-reactor (TT1) to the temperature controller (TIC1).</li>
	<li>Turn on the motor driving the external magnet to a speed of 120 rpm.</li>
	<li>Pressurize the setup to the desired set-point. 
	NOTE: Atmospheric pressure runs are performed by opening all outlet valves to the vent. Batch experiments can be performed by closing valve V4. Experiments under a constant head of pressure (preferable for high-pressure conditions) can be carried out by using the back-pressure regulator PV2.</li>
</ol>
3. Regular Procedure for the Visualization of Cracking Reactions
<ol>
	<li>Throughout the entire experiment, place the microscope objective under the reactor only when visualizing the sample or taking a snapshot. Avoid leaving the microscope objective under the reactor when it is not needed. 
	NOTE: Leaving the microscope objective under the reactor at high temperatures will cause an artificial brightening of the images, resulting in poor data, and may lead to a deterioration of the objective.</li>
	<li>Turn the temperature controller on and apply a temperature set-point of 200 &#176;C. Once the sample temperature reaches 200 &#176;C, perform a round of verifications. 
	NOTE: A round of verifications entails verifying the pressure, temperature, reactor position, focal distance of the microscope objectives, and stirring. As the temperature changes, the platform supporting the reactor and the heating assembly deforms slightly, so the vertical position of the microscope objective must be adjusted for the sapphire/sample interface to remain in focus. Stirring can be detected by the motion of the 1/16&#34; ferrule or of small heterogeneity in the sample (such as small mineral solids).</li>
	<li>If everything is in order as the sample reaches 200 &#176;C, perform a set-point change to 300 &#176;C. Once the sample temperature reaches 300 &#176;C, perform another round of verifications.</li>
	<li>Repeat the previous step, with 350 &#176;C as the new temperature set-point. 
	NOTE: 350 &#176;C can generally be considered as the higher temperature limit where cracking reactions are not significant (in the time scale of min).</li>
	<li>Change the set-point temperature to the desired reaction temperature, generally in the 400-450 &#176;C range.</li>
	<li>After making the final temperature set-point change, begin monitoring the reaction and recording data at regular time intervals, preferably every min.
	<ol>
		<li>Carry out each step of data recording as follows: rotate the nosepiece of the microscope to place the objective under the reactor. Adjust the focus. Take a snapshot. Rotate the nosepiece to move the objective away from underneath the reactor. Note the temperature. 
		NOTE: For future quantitative image analyses, snapshots should be taken with consistent settings throughout the experiment, namely in terms of magnification, lighting conditions, and camera acquisition settings (photosensitivity response and exposure time). As guidelines, the micrographs presented in this manuscript were taken with 100X magnification, maximum lighting conditions (using a halogen lightbulb), linear sensitivity response of the camera, and exposure times ranging from 200-400 ms.</li>
		<li>Perform the data recording steps repeatedly for as long as needed. 
		NOTE: Generally, the duration of the observation is guided by visual changes in the sample (color, brightness, and heterogeneity) or by an estimate of reaction conversion. 
		NOTE: Preferably, avoid continuing the experiment after the formation of large amounts of mesophase coke (which makes the reactor more difficult to clean).</li>
	</ol>
	</li>
</ol>
4. Shutdown and Clean-up
<ol>
	<li>Terminate the experiment by turning the temperature controller and the stirrer off and depressurizing the setup. Let the reactor cool. 
	NOTE: Cooling the reactor can be facilitated by removing the micro-reactor from the casing and out of the heating assembly. Applying a cool air flow to the micro-reactor can also make this process faster and easier.
	<ol>
		<li>Once the micro-reactor is cooled to room temperature, disconnect it from the gas lines of the setup, place it in a vice to loosen the bottom nut, and unseal the micro-reactor.</li>
	</ol>
	</li>
	<li>In a fume hood, take the micro-reactor apart by removing the bottom nut, the brass pad, the sapphire window, the 1/16&#34; ferrule, and the magnet. Remove the sealing ring. 
	NOTE: Coke may have formed during the experiment, which may cause the 1/16&#34; ferrule and the magnet to be stuck to the thermocouple.
	<ol>
		<li>Use tweezers to pull the 1/16&#34; ferrule and the magnets out. Use a spatula to lever the sealing ring out of the sealing groove. However, take care not to scratch the sealing groove in the process.</li>
	</ol>
	</li>
	<li>To remove the bulk of the material stuck to the micro-reactor walls, scrub the inside cavity of the micro-reactor with solvent-soaked (toluene or dichloromethane) pieces of paper towels. Repeat the process with pieces of emery cloth, preferably coarse grit (#100). 
	NOTE: During this process, do not scratch the sealing surfaces. At the end of this step, the metallic shine of stainless steel inside the micro-reactor cavity should be apparent.</li>
	<li>Remove the material stuck to the flat surfaces of the custom-machined magnet using a piece of emery cloth, preferably coarse grit (#100).
	<ol>
		<li>Use a solvent-soaked 1/16&#34; wire to remove the material stuck inside the hole of the custom-machined magnet.</li>
	</ol>
	</li>
	<li>Use solvent-soaked (toluene, dichloromethane, or acetone) cotton swabs to remove the material stuck to the sapphire window.</li>
	<li>To remove the remainder of the material stuck to the reactor walls, including the sealing surfaces, use solvent-soaked (toluene or dichloromethane) cotton swabs. 
	NOTE: The cleanup process is finished when, after scrubbing with a solvent-soaked cotton swab, the cotton swab comes out with negligible traces on it. 
	NOTE: However tedious this process might be, this step is important to avoid cross-contamination between experiments.</li>
	<li>Let the micro-reactor air-dry.</li>
</ol>
5. Image Analysis9
<ol>
	<li>Extract information from micrographs pertaining to the mean values of the red, green, and blue (RGB) channels, as well as the corresponding information in the hue, saturation, and intensity (HSI) color space. 
	NOTE: The HSI color space is described by cylindrical coordinates, where hue, saturation and intensity correspond to the angular, radial, and vertical coordinates, respectively. The relationships between the RGB values of a pixel and the corresponding HSI values are given by the following equations12,13, where m is the minimum of RGB values, while &#945; and &#946; are the pair of chromaticity coordinates:</li>
</ol>
<img alt="Equation 1" src="/files/ftp_upload/55246/55246eq1.jpg" />&#160; Eq. 1
<img alt="Equation 2" src="/files/ftp_upload/55246/55246eq2.jpg" />&#160; Eq. 2
<img alt="Equation 3" src="/files/ftp_upload/55246/55246eq3.jpg" />&#160; Eq. 3
<img alt="Equation 4" src="/files/ftp_upload/55246/55246eq4.jpg" />&#160; Eq. 4
<img alt="Equation 5" src="/files/ftp_upload/55246/55246eq5.jpg" />&#160; Eq. 5
<img alt="Equation 6" src="/files/ftp_upload/55246/55246eq6.jpg" />&#160; Eq. 6

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The authors have nothing to disclose.

Critical Steps within the Protocol
The first critical step in the protocol is ensuring the integrity of the metal-to-sapphire seal, especially if the experiment is to be carried out under pressure. Thus, the parallelism, the smoothness, and the cleanliness of the sealing surfaces should be carefully inspected, and the leak tests should be thorough. Since the modulus of rupture of sapphire is a decreasing function of temperature14, thicker sapphire windows should be used fo...

The study of the phase behavior of oil samples in a wide range of temperatures, pressures, and reactive conditions can yield very useful information for the operator of a refinery that processes a variety of feeds. In particular, the fouling of process units and lines by an uncontrolled formation of coke or sediments can severely affect production (loss of throughput) and energy efficiency (increase in heat transfer resistance)1,2,3. Possible plugging caused by the accumulation of fouling material may require a shutdown for clean-up purposes, which would have a highly negative economic impact4. Conducting an assessment of the fouling propensities of feeds can be highly valuable for the optimization of process conditions5 and the blending of refinery streams.
We have developed an in situ analyzer of petroleum stability in our laboratory to allow the visualization of oil samples subject to refinery process conditions. This apparatus relies on a specifically designed reactor made of stainless steel fittings and equipped with a sealed sapphire window at the bottom. The main principle of the device is the illumination of the sample inside the reactor at the desired range of temperature and pressure and the imaging of the resulting cross-polarized reflection. While previous published work relative to this setup focused on thermal cracking processes to emulate visbreaking conditions6,7,8,9 (which do not require high pressure), the reactor design was overhauled to investigate the behavior of samples under hydroconversion (catalytic cracking under high H2 pressure) and aquathermal10 (thermal cracking under high-pressure steam) conditions. Thus, the device was revised in order to operate in the 20-450 &#176;C temperature range and the 0.1-16 MPa pressure range, with the ability to sustain both 450 &#176;C and 16 MPa for reaction times of up to 6 h.
The first level of analysis on the visual information of the samples under a particular range of temperature, pressure, and reactive conditions is to determine whether the sample is single-phase or multiphase. This system is unique in that it allows for the visualization of opaque isotropic material and is not limited to the visualization of anisotropic material described in other work11. While the main indicator of the fouling propensity of samples is the tendency to drop sediments out of the bulk liquid; gas-liquid, liquid-liquid, liquid-solid, and more complex phase behaviors can be observed. However, valuable information can also be extracted from the visual evolution of a liquid as it remains homogeneous (single-phase). In particular, the brightness of the images is related to the refractive index and the extinction coefficient of the sample, while the color of the sample is a subset of its spectral information in the visible light range (380-700 nm), which can be used as a descriptor of its chemistry9.

<table><tbody><tr><td>Sapphire window, C-plane, 3 mm thick - 20 mm diam., Scratch/Dig: 80/50</td><td>Guild Optical Associates</td><td></td><td></td></tr><tr><td>C-seal</td><td>American Seal &amp;amp; Engineering</td><td>31005</td><td></td></tr><tr><td>Type-K thermocouple</td><td>Omega</td><td>KMQXL-062U-9&amp;nbsp;</td><td></td></tr><tr><td>Ferrule (1/16&quot;)</td><td>Swagelok</td><td>SS-103-1</td><td>Inserted for creating a clearance gap between the magnet and the window surface</td></tr><tr><td>Coil Heater</td><td>OEM Heaters</td><td>K002441</td><td></td></tr><tr><td>Temperature controller</td><td>Omron</td><td>E5CK</td><td></td></tr><tr><td>Inverted microscope</td><td>Zeiss</td><td>Axio Observer.D1m</td><td>Require cross-polarizer module</td></tr><tr><td>Toluene, 99.9% HPLC Grade</td><td>Fisher</td><td>Catalog # T290-4</td><td>Harmful, to be handled in fume hood</td></tr><tr><td>Methylene chloride, 99.9% HPLC Grade</td><td>Fisher</td><td>Catalog # D143-4</td><td>Harmful, to be handled in fume hood</td></tr><tr><td>Acetone, 99.7 Certified ACS Grade</td><td>Fisher</td><td>Catalog # A18P-4</td><td></td></tr></tbody></table>

in situ visualization of the phase behavior of oil samples under refinery process conditions

To help address production issues in refineries caused by the fouling of process units and lines, we have developed a setup as well as a method to visualize the behavior of petroleum samples under process conditions. The experimental setup relies on a custom-built micro-reactor fitted with a sapphire window at the bottom, which is placed over the objective of an inverted microscope equipped with a cross-polarizer module. Using reflection microscopy enables the visualization of opaque samples, such as petroleum vacuum residues, or asphaltenes. The combination of the sapphire window from the micro-reactor with the cross-polarizer module of the microscope on the light path allows high-contrast imaging of isotropic and anisotropic media. While observations are carried out, the micro-reactor can be heated to the temperature range of cracking reactions (up to 450 &#176;C), can be subjected to H2 pressure relevant to hydroconversion reactions (up to 16 MPa), and can stir the sample by magnetic coupling. 
Observations are typically carried out by taking snapshots of the sample under cross-polarized light at regular time intervals. Image analyses may not only provide information on the temperature, pressure, and reactive conditions yielding phase separation, but may also give an estimate of the evolution of the chemical (absorption/reflection spectra) and physical (refractive index) properties of the sample before the onset of phase separation.

The visual evolution of Athabasca Vacuum Residue is representative of the behavior of asphaltenic heavy crude oil samples and asphaltenic vacuum residue samples under thermal cracking conditions. However, using different samples and/or different temperature, pressure, or reaction conditions can give rise to a wide variety of phase behaviors. Micrographs corresponding to the thermal cracking experiment on an Athabasca Vacuum Residue sample at final set-point conditions of 435 &#176;C and P...

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In Situ Visualization of the Phase Behavior of Oil Samples Under Refinery Process Conditions

This article describes a setup and method for the in situ visualization of oil samples under a variety of temperature and pressure conditions that aim to emulate refining and upgrading processes. It is primarily used for studying isotropic and anisotropic media involved in the fouling behavior of petroleum feeds.

In Situ Visualization of the Phase Behavior of Oil Samples Under Refinery Process Conditions

To help address production issues in refineries caused by the fouling of process units and lines, we have developed a setup as well as a method to ...

in-situ-visualization-phase-behavior-oil-samples-under-refinery

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6.6K Views.  University of Alberta. This article describes a setup and method for the in situ visualization of oil samples under a variety of temperature and pressure conditions that aim to emulate refining and upgrading processes. It is primarily used for studying isotropic and anisotropic media involved in the fouling behavior of petroleum feeds.

Video: In Situ Visualization of the Phase Behavior of Oil Samples Under Refinery Process Conditions

Biomass Conversion to Produce Hydrocarbon Liquid Fuel Via Hot-vapor Filtered Fast Pyrolysis and Catalytic Hydrotreating

Lignocellulosic biomass conversion to produce biofuels has received significant attention because of the quest for a replacement for fossil fuels. Among the various thermochemical and biochemical routes, fast pyrolysis followed by catalytic hydrotreating is considered to be a promising near-term opportunity. This paper reports on experimental methods used 1) at the National Renewable Energy Laboratory (NREL) for fast pyrolysis of lignocellulosic biomass to produce bio-oils in a fluidized-bed reactor and 2) at Pacific Northwest National Laboratory (PNNL) for catalytic hydrotreating of bio-oils in a two-stage, fixed-bed, continuous-flow catalytic reactor. The configurations of the reactor systems, the operating procedures, and the processing and analysis of feedstocks, bio-oils, and biofuels are described in detail in this paper. We also demonstrate hot-vapor filtration during fast pyrolysis to remove fine char particles and inorganic contaminants from bio-oil. Representative results showed successful conversion of biomass feedstocks to fuel-range hydrocarbon biofuels and, specifically, the effect of hot-vapor filtration on bio-oil production and upgrading. The protocols provided in this report could help to generate rigorous and reliable data for biomass pyrolysis and bio-oil hydrotreating research.

Experimental methods for fast pyrolysis of lignocellulosic biomass to produce bio-oils and for the catalytic hydrotreating of bio-oils to produce fuel range hydrocarbons are presented. Hot-vapor filtration during fast pyrolysis to remove fine char particles and inorganic contaminants from bio-oil was also assessed.

Lignocellulosic biomass conversion to produce biofuels has received significant attention because of the quest for a replacement for fossil fuels. Among ...

Biochemistry

High-pressure Sapphire Cell for Phase Equilibria Measurements of CO2/Organic/Water Systems

The high pressure sapphire cell apparatus was constructed to visually determine the composition of multiphase systems without physical sampling. Specifically, the sapphire cell enables visual data collection from multiple loadings to solve a set of material balances to precisely determine phase composition. Ternary phase diagrams can then be established to determine the proportion of each component in each phase at a given condition. In principle, any ternary system can be studied although ternary systems (gas-liquid-liquid) are the specific examples discussed herein. For instance, the ternary THF-Water-CO2 system was studied at 25 and 40&#160;&#176;C and is described herein. Of key importance, this technique does not require sampling. Circumventing the possible disturbance of the system equilibrium upon sampling, inherent measurement errors, and technical difficulties of physically sampling under pressure is a significant benefit of this technique. Perhaps as important, the sapphire cell also enables the direct visual observation of the phase behavior. In fact, as the CO2 pressure is increased, the homogeneous THF-Water solution phase splits at about 2 MPa. With this technique, it was possible to easily and clearly observe the cloud point and determine the composition of the newly formed phases as a function of pressure.
The data acquired with the sapphire cell technique can be used for many applications. In our case, we measured swelling and composition for tunable solvents, like gas-expanded liquids, gas-expanded ionic liquids and Organic Aqueous Tunable Systems (OATS)1-4. For the latest system, OATS, the high-pressure sapphire cell enabled the study of (1) phase behavior as a function of pressure and temperature, (2) composition of each phase (gas-liquid-liquid) as a function of pressure and temperature and (3) catalyst partitioning in the two liquid phases as a function of pressure and composition. Finally, the sapphire cell is an especially effective tool to gather accurate and reproducible measurements in a timely fashion.

High-pressure Sapphire Cell for Phase Equilibria Measurements of CO2/Organic/Water Systems

The high pressure sapphire cell apparatus is a unique tool to study, without sampling, phase behavior under a wide range of pressures. Using a cathetometer, very precise volume measurements can be recorded to measure liquid expansion and phase composition. Thus, this synthetic method enables the study of (1) phase equilibria of multi-component mixtures and (2) the partition behavior of catalyst or model compounds as a function of pressure.

The high pressure sapphire cell apparatus was constructed to visually determine the composition of multiphase systems without physical sampling. ...

Chemistry

Chemical Analysis of Water-accommodated Fractions of Crude Oil Spills Using TIMS-FT-ICR MS

Multiple chemical processes control how crude oil is incorporated into seawater and also the chemical reactions that occur overtime. Studying this system requires the careful preparation of the sample in order to accurately replicate the natural formation of the water-accommodated fraction that occurs in nature. Low-energy water-accommodated fractions (LEWAF) are carefully prepared by mixing crude oil and water at a set ratio. Aspirator bottles are then irradiated, and at set time points, the water is sampled and extracted using standard techniques. A second challenge is the representative characterization of the sample, which must take into consideration the chemical changes that occur over time. A targeted analysis of the aromatic fraction of the LEWAF can be performed using an atmospheric-pressure laser ionization source coupled to a custom-built trapped ion mobility spectrometry&#8211;Fourier transform&#8211;ion cyclotron resonance mass spectrometer (TIMS-FT-ICR MS). The TIMS-FT-ICR MS analysis provides high-resolution ion mobility and ultrahigh-resolution MS analysis, which further allow the identification of isomeric components by their collision cross-sections (CCS) and chemical formula. Results show that as the oil-water mixture is exposed to light, there is significant photo-solubilization of the surface oil into the water. Over time, the chemical transformation of the solubilized molecules takes place, with a decrease in the number of identifications of nitrogen- and sulfur-bearing species in favor of those with a greater oxygen content than were typically observed in the base oil.

The low-energy water-accommodated fraction (LEWAF) of crude oil is a challenging system to analyze, because over time, this complex mixture undergoes chemical transformations. This protocol illustrates methods for the preparation of the LEWAF sample and for performing photo-irradiation and chemical analysis by trapped ion mobility spectrometry&#8211;FT-ICR MS.

Multiple chemical processes control how crude oil is incorporated into seawater and also the chemical reactions that occur overtime. Studying this system ...

Environment

Phase Diagram Characterization Using Magnetic Beads as Liquid Carriers

Magnetic beads with ~1.9 &#181;m average diameter were used to transport microliter volumes of liquids between contiguous liquid segments with a tube for the purpose of investigating phase change of those liquid segments. The magnetic beads were externally controlled using a magnet, allowing for the beads to bridge the air valve between the adjacent liquid segments. A hydrophobic coating was applied to the inner surface of the tube to enhance the separation between two liquid segments. The applied magnetic field formed an aggregate cluster of magnetic beads, capturing a certain liquid amount within the cluster that is referred to as carry-over volume. A fluorescent dye was added to one liquid segment, followed by a series of liquid transfers, which then changed the fluorescence intensity in the neighboring liquid segment. Based on the numerical analysis of the measured fluorescence intensity change, the carry-over volume per mass of magnetic beads has been found to be ~2 to 3 &#181;l/mg. This small amount of liquid allowed for the use of comparatively small liquid segments of a couple hundred microliters, enhancing the feasibility of the device for a lab-in-tube approach. This technique of applying small compositional variation in a liquid volume was applied to analyzing the binary phase diagram between water and the surfactant C12E5 (pentaethylene glycol monododecyl ether), leading to quicker analysis with smaller sample volumes than conventional methods.

Here, we present a protocol to investigate multi-component phase diagrams using externally controlled magnetic beads as liquid carriers in a lab-in-tube approach. This approach can aid in applications that seek to gather further information on phase change in complex liquid systems.

Magnetic beads with ~1.9 &#181;m average diameter were used to transport microliter volumes of liquids between contiguous liquid segments with a tube for ...

Measurement of the Rheology of Crude Oil in Equilibrium with CO2 at Reservoir Conditions

A rheometer system to measure the rheology of crude oil in equilibrium with carbon dioxide (CO2) at high temperatures and pressures is described. The system comprises a high-pressure rheometer which is connected to a circulation loop. The rheometer has a rotational flow-through measurement cell with two alternative geometries: coaxial cylinder and double gap. The circulation loop contains a mixer, to bring the crude oil sample into equilibrium with CO2, and a gear pump that transports the mixture from the mixer to the rheometer and recycles it back to the mixer. The CO2 and crude oil are brought to equilibrium by stirring and circulation and the rheology of the saturated mixture is measured by the rheometer. The system is used to measure the rheological properties of Zuata crude oil (and its toluene dilution) in equilibrium with CO2 at elevated pressures up to 220 bar and a temperature of 50 &#176;C. The results show that CO2 addition changes the oil rheology significantly, initially reducing the viscosity as the CO2 pressure is increased and then increasing the viscosity above a threshold pressure. The non-Newtonian response of the crude is also seen to change with the addition of CO2.

Measurement of the Rheology of Crude Oil in Equilibrium with CO2 at Reservoir Conditions

A method for measuring the rheology of crude oil in equilibrium with carbon dioxide at reservoir conditions is presented.

A rheometer system to measure the rheology of crude oil in equilibrium with carbon dioxide (CO2) at high temperatures and pressures is described. The ...

Microfluidic Devices for Characterizing Pore-scale Event Processes in Porous Media for Oil Recovery Applications

Microfluidic devices are versatile tools for studying transport processes at a microscopic scale. A demand exists for microfluidic devices that are resistant to low molecular-weight oil components, unlike traditional polydimethylsiloxane (PDMS) devices. Here, we demonstrate a facile method for making a device with this property, and we use the product of this protocol for examining the pore-scale mechanisms by which foam recovers crude oil. A pattern is first designed using computer-aided design (CAD) software and printed on a transparency with a high-resolution printer. This pattern is then transferred to a photoresist via a lithography procedure. PDMS is cast on the pattern, cured in an oven, and removed to obtain a mold. A thiol-ene crosslinking polymer, commonly used as an optical adhesive (OA), is then poured onto the mold and cured under UV light. The PDMS mold is peeled away from the optical adhesive cast. A glass substrate is then prepared, and the two halves of the device are bonded together. Optical adhesive-based devices are more robust than traditional PDMS microfluidic devices. The epoxy structure is resistant to swelling by many organic solvents, which opens new possibilities for experiments involving light organic liquids. Additionally, the surface wettability behavior of these devices is more stable than that of PDMS. The construction of optical adhesive microfluidic devices is simple, yet requires incrementally more effort than the making of PDMS-based devices. Also, though optical adhesive devices are stable in organic liquids, they may exhibit reduced bond-strength after a long time. Optical adhesive microfluidic devices can be made in geometries that act as 2-D micromodels for porous media. These devices are applied in the study of oil displacement to improve our understanding of the pore-scale mechanisms involved in enhanced oil recovery and aquifer remediation.

The goal of this procedure is to easily and rapidly produce a microfluidic device with customizable geometry and resistance to swelling by organic fluids for oil recovery studies. A polydimethylsiloxane mold is first generated, and then used to cast the epoxy-based device. A representative displacement study is reported.

Microfluidic devices are versatile tools for studying transport processes at a microscopic scale. A demand exists for microfluidic devices that are ...

On-line Analysis of Nitrogen Containing Compounds in Complex Hydrocarbon Matrixes

The shift to heavy crude oils and the use of alternative fossil resources such as shale oil are a challenge for the petrochemical industry. The composition of heavy crude oils and shale oils varies substantially depending on the origin of the mixture. In particular they contain an increased amount of nitrogen containing compounds compared to the conventionally used sweet crude oils. As nitrogen compounds have an influence on the operation of thermal processes occurring in coker units and steam crackers, and as some species are considered as environmentally hazardous, a detailed analysis of the reactions involving nitrogen containing compounds under pyrolysis conditions provides valuable information. Therefore a novel method has been developed and validated with a feedstock containing a high nitrogen content, i.e., a shale oil. First, the feed was characterized offline by comprehensive two-dimensional gas chromatography (GC &#215; GC) coupled with a nitrogen chemiluminescence detector (NCD). In a second step the on-line analysis method was developed and tested on a steam cracking pilot plant by feeding pyridine dissolved in heptane. The former being a representative compound for one of the most abundant classes of compounds present in shale oil. The composition of the reactor effluent was determined via an in-house developed automated sampling system followed by immediate injection of the sample on a GC &#215; GC coupled with a time-of-flight mass spectrometer (TOF-MS), flame ionization detector (FID) and NCD. A novel method for quantitative analysis of nitrogen containing compounds using NCD and 2-chloropyridine as an internal standard has been developed and demonstrated.

A method combining comprehensive two-dimensional gas chromatography with nitrogen chemiluminescence detection has been developed and applied to on-line analysis of nitrogen containing compounds in a complex hydrocarbon matrix.

The shift to heavy crude oils and the use of alternative fossil resources such as shale oil are a challenge for the petrochemical industry. The ...

Laboratory Production of Biofuels and Biochemicals from a Rapeseed Oil through Catalytic Cracking Conversion

The work is based on a reported study which investigates the processability of canola oil (bio-feed) in the presence of bitumen-derived heavy gas oil (HGO) for production of transportation fuels through a fluid catalytic cracking (FCC) route. Cracking experiments are performed with a fully automated reaction unit at a fixed weight hourly space velocity (WHSV) of 8 hr-1, 490-530 &#176;C, and catalyst/oil ratios of 4-12 g/g. When a feed is in contact with catalyst in the fluid-bed reactor, cracking takes place generating gaseous, liquid, and solid products. The vapor produced is condensed and collected in a liquid receiver at -15 &#176;C. The non-condensable effluent is first directed to a vessel and is sent, after homogenization, to an on-line gas chromatograph (GC) for refinery gas analysis. The coke deposited on the catalyst is determined in situ by burning the spent catalyst in air at high temperatures. Levels of CO2 are measured quantitatively via an infrared (IR) cell, and are converted to coke yield. Liquid samples in the receivers are analyzed by GC for simulated distillation to determine the amounts in different boiling ranges, i.e., IBP-221 &#176;C (gasoline), 221-343 &#176;C (light cycle oil), and 343 &#176;C+ (heavy cycle oil). Cracking of a feed containing canola oil generates water, which appears at the bottom of a liquid receiver and on its inner wall. Recovery of water on the wall is achieved through washing with methanol followed by Karl Fischer titration for water content. Basic results reported include conversion (the portion of the feed converted to gas and liquid product with a boiling point below 221 &#176;C, coke, and water, if present) and yields of dry gas (H2-C2's, CO, and CO2), liquefied petroleum gas (C3-C4), gasoline, light cycle oil, heavy cycle oil, coke, and water, if present.

This paper presents an experimental method to produce biofuels and biochemicals from canola oil mixed with a fossil-based feed in the presence of a catalyst at mild temperatures. Gaseous, liquid, and solid products from a reaction unit are quantified and characterized. Conversion and individual product yields are calculated and reported.

The work is based on a reported study which investigates the processability of canola oil (bio-feed) in the presence of bitumen-derived heavy gas oil ...

Experimental Procedure for Laboratory Studies of In Situ Burning : Flammability and Burning Efficiency of Crude Oil

A new method for the simultaneous study of the flammability and burning efficiency of fresh and weathered crude oil through two experimental laboratory setups is presented. The experiments are easily repeatable compared to operational scale experiments (pool diameter &#8805;2 m), while still featuring quite realistic in situ burning conditions of crude oil on water. Experimental conditions include a flowing water sub-layer that cools the oil slick and an external heat flux (up to 50 kW/m2) that simulates the higher heat feedback to the fuel surface in operational scale crude oil pool fires. These conditions enable a controlled laboratory study of the burning efficiency of crude oil pool fires that are equivalent to operational scale experiments. The method also provides quantitative data on the requirements for igniting crude oils in terms of the critical heat flux, ignition delay time as a function of the incident heat flux, the surface temperature upon ignition, and the thermal inertia. This type of data can be used to determine the required strength and duration of an ignition source to ignite a certain type of fresh or weathered crude oil. The main limitation of the method is that the cooling effect of the flowing water sub-layer on the burning crude oil as a function of the external heat flux has not been fully quantified. Experimental results clearly showed that the flowing water sub-layer does improve how representative this setup is of in situ burning conditions, but to what extent this representation is accurate is currently uncertain. The method nevertheless features the most realistic in situ burning laboratory conditions currently available for simultaneously studying the flammability and burning efficiency of crude oil on water.

Experimental Procedure for Laboratory Studies of In Situ Burning : Flammability and Burning Efficiency of Crude Oil

Here, we present a protocol to simultaneously study the flammability and burning efficiency of fresh and weathered crude oil under conditions that simulate in situ burning operations on the sea.

A new method for the simultaneous study of the flammability and burning efficiency of fresh and weathered crude oil through two experimental laboratory ...

Combining Microfluidics and Microrheology to Determine Rheological Properties of Soft Matter during Repeated Phase Transitions

The microstructure of soft matter directly impacts macroscopic rheological properties and can be changed by factors including colloidal rearrangement during previous phase changes and applied shear. To determine the extent of these changes, we have developed a microfluidic device that enables repeated phase transitions induced by exchange of the surrounding fluid and microrheological characterization while limiting shear on the sample. This technique is &#181;2rheology, the combination of microfluidics and microrheology. The microfluidic device is a two-layer design with symmetric inlet streams entering a sample chamber that traps the gel sample in place during fluid exchange. Suction can be applied far away from the sample chamber to pull fluids into the sample chamber. Material rheological properties are characterized using multiple particle tracking microrheology (MPT). In MPT, fluorescent probe particles are embedded into the material and the Brownian motion of the probes is recorded using video microscopy. The movement of the particles is tracked and the mean-squared displacement (MSD) is calculated. The MSD is related to macroscopic rheological properties, using the Generalized Stokes-Einstein Relation. The phase of the material is identified by comparison to the critical relaxation exponent, determined using time-cure superposition. Measurements of a fibrous colloidal gel illustrate the utility of the technique. This gel has a delicate structure that can be irreversibly changed when shear is applied. &#181;2rheology data shows that the material repeatedly equilibrates to the same rheological properties after each phase transition, indicating that phase transitions do not play a role in microstructural changes. To determine the role of shear, samples can be sheared prior to injection into our microfluidic device. &#181;2rheology is a widely applicable technique for the characterization of soft matter enabling the determination of rheological properties of delicate microstructures in a single sample during phase transitions in response to repeated changes in the surrounding environmental conditions.

We demonstrate the fabrication and use of a microfluidic device that enables multiple particle tracking microrheology measurements to study the rheological effects of repeated phase transitions on soft matter.

The microstructure of soft matter directly impacts macroscopic rheological properties and can be changed by factors including colloidal rearrangement ...

In Situ Visualization of the Phase Behavior of Oil Samples Under Refinery Process Conditions

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Biomass Conversion to Produce Hydrocarbon Liquid Fuel Via Hot-vapor Filtered Fast Pyrolysis and Catalytic Hydrotreating

High-pressure Sapphire Cell for Phase Equilibria Measurements of CO₂/Organic/Water Systems

Chemical Analysis of Water-accommodated Fractions of Crude Oil Spills Using TIMS-FT-ICR MS

Phase Diagram Characterization Using Magnetic Beads as Liquid Carriers

Measurement of the Rheology of Crude Oil in Equilibrium with CO₂ at Reservoir Conditions

Microfluidic Devices for Characterizing Pore-scale Event Processes in Porous Media for Oil Recovery Applications

On-line Analysis of Nitrogen Containing Compounds in Complex Hydrocarbon Matrixes

Laboratory Production of Biofuels and Biochemicals from a Rapeseed Oil through Catalytic Cracking Conversion

Experimental Procedure for Laboratory Studies of In Situ Burning : Flammability and Burning Efficiency of Crude Oil

Combining Microfluidics and Microrheology to Determine Rheological Properties of Soft Matter during Repeated Phase Transitions