OUR JOURNEY

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From Past to Present

Tracing SCFCan's History, Research, and Publications

Warren Stiver, one of SCFCan’s founders, initiated supercritical fluid Research, Design and Development work as far back as 1991.  The goal, although not fully articulated at that time, was to bring the supercritical (SC) fluid technology, specifically Supercritical Fluid Extraction (SFE), to commercial success for environmental benefits. Contaminated site remediation was the initial target application but overtime the application breadth has increased considerably.

Bringing a process technology to commercial success i.e., bringing it along the Technology Readiness Level (TRL) path, requires several stages from proof of concepts, process scale-up, and ultimately to commercial rollout.  In parallel with all of these stages is the measurement of fundamental properties, model development, economic evaluation, and system safety and control.

Proof of concepts is an important and essential element on the technology development path.  Concepts to prove can range from the essence of the technology – in SFE context, this would involve proving whether compound “A” can be extracted from matrix “X”.  Proof also includes whether a valve, pump, sensor, or other item can work as the technology evolves through scale-up, even if it has been previously shown by others. 

Our bench scale systems have been successfully used for various applications, including to extract PAHs and chlorinated organics from soils, drilling fluids from drilling waste, bitumen from process wastes and process streams, hydrocarbons from oil sand, oils from tree waste, oils from spent coffee grounds, and oils from municipal waste.

Some of these extracts are shown below.

  1. Click to view publications!
    • Guigard S.E., LaPlante T., Stiver W.H., Zytner R.G. 1999. Soil Remediation using Supercritical Fluid Extraction, Environmental Research and Technology Development Forum for the Upstream Oil and Gas Industry, Calgary, Alberta, Canada.
    • Odusanya O., Guigard, S.E. 2001. Treatment of Oil-Contaminated Drill Cuttings Using Supercritical Carbon Dioxide, Drilling Waste Management Forum, Calgary, Alberta, Canada.
    • Savoie N., Guigard S.E. 2001. Supercritical Fluid Extraction of Metals from Soils, Proc. 6th Conference on Supercritical Fluids and their Applications, Maiori, Italy.
    • Odusanya O.O. 2003. Supercritical Carbon Dioxide Treatment of Oil Contaminated Drill Cuttings. MSc Thesis, Department of Civil & Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada.
    • Nagpal V., Guigard S.E. 2003. Remediation Of Flare Pit Soils Using Supercritical Fluid Extraction, Proc. 6th International Symposium on Supercritical Fluids, Versailles, France.
    • Lopez-Gomez J.J. 2006. The Use of Supercritical Fluid Extraction for the Treatment of Oil Contaminated Drilling Waste. MSc Thesis, Department of Civil & Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada.
    • Street C.G., Tesche C., Guigard S.E. 2007. Treatment of Hydrocarbon-Based Drilling Waste Using Supercritical Carbon Dioxide, SPE E&P Environmental and Safety Conference, Galveston, Texas, USA.
    • Guigard S.E., Stiver W.H. 2008. Supercritical Fluid Extraction: A Non-Aqueous Technology for the Extraction of Bitumen from Oil Sands, Proc. World Heavy Oil Congress, Edmonton, Canada.
    • Fang Y. 2010. Extraction of Hydrocarbons from Oil sand using Supercritical Carbon Dioxide. MSc. Thesis, Department of Civil & Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada.
    • Jones C.R. 2010. Treatment of Oily Drill Cuttings Slurries using Supercritical Carbon Dioxide. MSc Thesis, Department of Civil & Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada.
    • La H., Guigard, S.E. 2015. Extraction of Hydrocarbons from Athabasca Oil sand Slurry using Supercritical Carbon Dioxide, Journal of Supercritical Fluids, V. 100, p. 146.
    • Underwood E., Guigard S.E., Stiver W.H., McMillan J., Bhattacharya S. 2018. Proc. 12th International Symposium on Supercritical Fluids, Antibes-Juan-les-Pins, France.
    • Cossey H.L., Guigard S.E., Underwood E., Stiver W.H., McMillan J., Bhattacharya S. 2018. Proc. 12th International Symposium on Supercritical Fluids, Antibes-Juan-les-Pins, France.
    • Cossey H.L. 2018. Extraction of Hydrocarbons from Bitumen and Bitumen-containing Process and Process Waste Streams using Supercritical Carbon Dioxide. MSc. Thesis, Department of Civil & Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada.
    • Cossey H.L., Guigard S.E., Underwood E., Stiver, W.H., McMillan J., Bhattacharya S. 2019. Supercritical Fluid Extraction of Bitumen using Chemically Modified Carbon Dioxide. Journal of Supercritical Fluids, 154:104599.
    • Yu E.H. 2021. Initial Solubility Measurements of Bitumen Cuts in Supercritical Carbon Dioxide. MSc. Thesis, Department of Civil & Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada.
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We have also proven the ability to operate a counter-current (SC-CO2 / slurry), continuous flow extractor. This is a first of its kind continuous solids processing system. It effectively recovered PAHs from contaminated soils.

Proof-of-concept developments are embedded in work at larger scales.  Primarily, this revolves around proving process control capability and the performance or development of new sensors.

A continuous pilot-scale system was designed, built, and commissioned based on the success at bench scale.  This pilot system proved capable of extracting drilling fluids from drilling wastes and bitumen from bitumen containing process streams. 

The high-quality drilling fluid extracted from the drilling waste (left) and the bitumen extracted from contaminated waste (right), using the pilot-scale fully continuous SFE system is shown here.

Commercial development of our fully-continuous technology, is the focus of our current work.

  1. Click to view publications!
    • Fortin M., Stiver W. 2003. Fully-Continuous Supercritical Fluid Extraction of Naphthalene from Soil Slurries, Proc. 6th International Symposium on Supercritical Fluids, Versailles, France, p. 481.
    • Forsyth, V.C. 2006. Fully-Continuous Supercritical Fluid Extraction of PAHs from Soil Slurries. MSc Thesis, School of Engineering, University of Guelph, Guelph, Ontario, Canada.
    • Ryan M., Stiver W. 2007. A Fully-Continuous Supercritical Fluid Extraction System for Contaminated Soil, Canadian Journal of Chemical Engineering, 85:233-239.
    • Roodpeyma M. 2017. Development, Modelling and Control of a Continuous Pilot Scale Supercritical Fluid Extraction Process. PhD Thesis, Department of Civil & Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada.
    • Street C. 2020. Construction, Operation, and Performance Evaluation of a Continuous Supercritical Fluid Extraction Process for the Recovery of Hydrocarbons from Drill Cuttings. PhD Thesis, Department of Civil & Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada.

Measurement of fundamental properties are essential to support technology development and deployment.  Thermodynamic properties are fundamental, and they are process scale independent.  Thermodynamic measurements have included:

    • Partition coefficients of polynuclear aromatic hydrocarbons (PAHs) and chlorinated organics between soils and SC-CO2
    • Solubility of metal chelates in SC-CO2 using piezoelectric quartz crystals
    • Solubility of drilling fluids (diesel, etc.) in SC-CO2
    • Pseudo-solubility of bitumen components (as characterized by High Temperature Simulated Distillation – HTSD) in SC-CO2 with and without cosolvents
  1. Click to view publications!
    • Gray D.J., Zytner R.G., Stiver W.H. 1995. Supercritical Carbon Dioxide - Soil Partition Coefficients, Journal of Supercritical Fluids, 8:149-155.
    • Guigard S., Hayward G.H., Zytner R.G., Stiver W.H. 1998. A New Technique for Measuring Solubilities in Supercritical Fluids: Application to the Measurement of Metal Chelate Solubilities, Proc. 5th Meeting on Supercritical Fluids: Materials and Natural Products Processing, Nice, France.
    • Guigard S.E., Hayward G.L., Zytner R.G., Stiver W.H. 2001. Measurement of Solubilities in Supercritical Fluids using a Piezoelectric Quartz Crystal, Fluid Phase Equilibria, 187-188:233-246.
    • Seifried B., Guigard S.E. 2003. Measurement Of Solubilities of Metal Chelates in Supercritical Carbon Dioxide Using a Quartz Crystal Microbalance, Proc. 6th International Symposium on Supercritical Fluids, Versailles, France.

Mass transfer behaviour and mass transfer coefficients are equally fundamental.  However, they are technology and scale dependent.  Mass transfer behaviour assessments have included:

    • Mass transfer coefficient of a wide range of compounds from soils and waste streams
    • Mass transfer coefficient under various mixing conditions e.g., unmixed, passive mixing, and active mixing
    • Mass transfer coefficients in a small, actively mixed batch extractor with and without the addition of water
    • Mass transfer coefficients at different SFE system scales

Mass Transfer Coefficient of Naphthalene vs. Density of Carbon Dioxide is shown here as an example (Data source, Forsyth 2006).

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    • Pratte T.S., Guigard, S., Zytner, R.G., Stiver, W.H. 1996. Influence of Water on Supercritical Fluid Extraction, Proc. 51st Annual Purdue Industrial Waste Conference, V.51, p. 95-105.
    • Smyth T.J., Zytner R.G., Stiver W.H. 1999. Influence of Water on the Supercritical Fluid Extraction of Naphthalene from Soil, Journal of Hazardous Materials, B67:183-196.
    • Street C., Guigard S., Kapila M., Smith A., Bingham R., Stiver W. 2013. Mass Transfer Coefficients for the Removal of Oil from Drill Cuttings Using Supercritical Carbon Dioxide, Proc. 10th Conference on Supercritical Fluids and their Applications, Naples, Italy.

Model development is an important aspect of technology development at all stages.

Thermodynamic properties are core to design and analysis at all system levels.  Span and Wagner’s Fundamental Equation of State (FEOS) is the recognized gold standard (Span R., Wagner W. 1996. J. of Physical Chem. Ref. Data, Vol. 25, p. 1509-1596).  We have an Objective C and Matlab versions of the FEOS to support our work (see SCFVirtual.ca). 

Solubility data for binary systems (predominantly solute / SC-CO2 systems) have been correlated with a new density-dependent solute solubility parameter and with Chrastil’s established model.  For ternary systems (solute, cosolvent and SC fluid), some efforts to predict behaviour has been pursued in addition to the use of the well-established Mendez-Santiago-Teja (MST) correlation.

Measured bitumen pseudo solubility data by High Temperature Simulated Distillation (HTSD) compositional breakdown has also been correlated using Chrastil and MST.  An example of the Chrastil fitting quality is seen here.

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    • Guigard S.E., Stiver W.H. 1998. A Density-Dependent Solute Solubility Parameter for Correlating Solubilities in Supercritical Fluids, Industrial and Engineering Chemistry Research, 37:3786-3792.
    • Stiver W.H., Guigard S.E., Beausoleil P. 2000. Predicting Ternary Solubilities using a Solubility Parameter Approach, Proc. 5th International Symposium on Supercritical Fluids, Atlanta, Georgia, USA.
    • Stiver W.H. 2021. Chrastil Revisited for Supercritical Carbon Dioxide, Journal of Supercritical Fluids, 177:105348

Mass balance and mass transfer models are necessary to calculate mass transfer coefficients from experimental extraction data.  These models depend on the physical nature of the extractor, on the operating strategy of the experiment and on the thermodynamic models.  We have built numerous models for our various physical setups and for our various designs. 

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    • Rahmé Z., Zytner R.G., Stiver W.H. 1995. Kinetic Model for the Supercritical Extraction of Contaminants from Soil, in Innovations in Supercritical Fluids: Science and Technology, Hutchenson K.W., Foster N.R. Eds., ACS Symposium Series #608, Washington D.C., Chapter 20, p. 298-312.
    • Smyth, T. 1996. The Influence of Water on the Supercritical Fluid Extraction of Naphthalene from Soil. MSc Thesis, School of Engineering, University of Guelph, Guelph, Ontario, Canada.
    • Fortin, M.F. 2003. Fully-Continuous Supercritical Fluid Extraction of Naphthalene from Soil Slurries. MSc Thesis, School of Engineering, University of Guelph, Guelph, Ontario, Canada.
    • Forsyth, V.C. 2006. Fully-Continuous Supercritical Fluid Extraction of PAHs from Soil Slurries. MSc Thesis, School of Engineering, University of Guelph, Guelph, Ontario, Canada.
    • Street C.G. 2008. Extraction of Hydrocarbons from Drilling Waste Using Supercritical Carbon Dioxide.MSc Thesis, Department of Civil & Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada.

In more complex and multi-vessel systems, it is valuable to build full system models.  Steady state and unsteady state models have been built.  Steady state models are coupled mass and energy balances that serve to aid in the overall system design and in determining component specifications and energy requirements.  Unsteady state models are essential for system control and operation.  Hydrodynamic models form a foundation for these unsteady state models. This simulator is used in various stages of technology development. A screenshot of the developed simulator by SCFCan, based on the hydrodynamic model of the fully continuous pilot-scale SFE system is presented below.

  1. Click to view publications!
    • Roodpeyma M., Street C., Guigard S.E., Stiver W.H. 2018. A Hydrodynamic Model of a Continuous Supercritical Fluid Extraction System for the Treatment of Oil Contaminated Solids, Separation Science and Technology, 53:44-60.
    • Roodpeyma M., Street C., Guigard S.E., Stiver W.H. 2022. A Real Time Simulator of a Supercritical Fluid Extraction (SFE) System, Proc. 13th International Symposium on Supercritical Fluids Montreal, Canada.

Economic evaluation is an important component of technology development and needs to be active at each stage along the TRL path. Solubility data is sufficient to provide a lower limit on the supercritical flow required and thus the basis for a minimum operating cost estimate associated with recirculating CO2 flow. Mass transfer coefficients provide a basis for initial equipment sizing and thereby a beginning for capital cost estimates. Our full system models have integrated in capital cost estimation and energy/operating cost estimation. 

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    • Rampley G., Stiver W. 2003. Optimizing Supercritical Fluid Extraction Systems, Proc. 6th International Symposium on Supercritical Fluids, Versailles, France, p. 611.

System safety is a particularly challenging dimension for supercritical fluid processes. Pressure ratings of all components must be sufficient to handle any plausible scenario for the experimental setup. As an additional precaution, all of our bench-scale work was conducted within a closed fume hood or within an enclosure (as shown in the bench scale continuous SFE system). Burst disks and pressure relief valves are necessary elements as systems get larger.

Our pilot system includes emergency shutdown features, tied to pressure sensors and to room ambient CO2 sensors. Personal CO2 dosimeters are also used as an extra precaution. 

Hazards and Operability Study (HAZOP), with support of our industrial sponsor, was an important part of our pilot system development.  All active systems development work uses HAZOP and FMEA (Failure Mode and Effects Analysis) to assist in minimizing risks. 

Connected to system safety is system control which has many elements and plays a role at all levels of technology development.  Early fundamental experimental work requires the ability to operate an experiment at known and steady temperature, pressure, and flows. 

Developing novel systems often leads to custom components including sensors.  Some of these developed novelties include:

    • A piezoelectric quartz crystal used to measure solute mass dissolution for solubility measurements
    • A unique flow restrictor, instead of a valve, developed for controlling flow for our slurry applications
    • Level control within our extractors which has required a different strategy at each technology scale

System control demands increase as scale increases.  Our pilot-scale fully continuous SFE system includes flow, pressure, level, and temperature control within a PI controller logic.  On the safety side, everything from alarms to emergency shutdowns are integrated into the control system and user interface. The control user interfaces for the pilot system are shown below.

Active work includes introducing model predictive control and control logic that minimizes energy use (GHG emissions) per unit of product as part of efforts towards net zero.

  1. Click to view publications!
    • Rosenthal A. 2012. Safe Design of a Continuous Supercritical Extraction System for the Extraction of Drilling Fluid from Drill Cuttings. MSc Thesis, School of Engineering, University of Guelph, Guelph, Ontario, Canada.
    • Roodpeyma M., Guigard S.E., Stiver W.H. 2018. Pressure Control of a Continuous Pilot Scale Supercritical Fluid Extraction (SFE) Process, Journal of Supercritical Fluids, 135:120-129.

Commercialization Journey Wrap-up and Future

SCFCan has made great strides in bringing a platform supercritical technology forward to near commercialization. SCFCan’s developed expertise transcends the TRL development path for supercritical processes.  We expect to see full rollout for multiple applications over the next few years.  Our technology offers high quality products from various waste streams contributing to a circular economy.  At the same time, low life cycle GHG emissions are realized while remaining economically profitable.