Project Synopsis

Develop process design information for a system to separate hexane from a mixture of Invert Oil and hexane.

Project Summary


Process Engineering Associates, LLC (PROCESS) was subcontracted by an international process engineering company to prepare a process design for a system to separate hexane from a light oil product associated with an overall Invert Oil Recovery System being developed by the ultimate client, a Canadian chemicals recovery concern.

Invert Oil is a mixture of light oils, water, and surfactants used as cutting oils in the oil & gas well drilling industry.  The overall Invert Oil recovery process includes treating drilling muds, which contain the Invert Oil, with hexane.  After a number of process steps, a clean solids-free mixture of hexane and Invert Oil is obtained.  PROCESS was subcontracted to prepare the preliminary process design and equipment sizing information for the separation and recovery of the hexane from the Invert Oil product.  The process design required development of equipment sizing, pipe sizing, and process control requirements information sufficient for use by a detail design firm to obtain a capital cost estimate for the overall project.

PROCESS developed and prepared an initial Design Basis to be used for all subsequent process design tasks based on data obtained from a Vacuum Flash Kettle separation process, which had been partially developed and piloted by the client.  An important aspect of the initial Design Basis was that at this point in the development of the process development, client-defined constraints on the maximum allowable temperature for the Invert Oil product dictated that the hexane–oil separation be carried out under vacuum conditions.

Also, as part of the Design Basis, a CHEMCAD simulation was prepared to correlate the closed cup flash point vs. wt% hexane in the Invert Oil.  This was required to define the specification for the maximum concentration of hexane that could be allowed in the Invert Oil product.

Initially, PROCESS performed a very preliminary CHEMCAD simulation for initial sizing and costing of a vacuum distillation column for comparison with the client-defined Vacuum Flash Kettle separation process.  Based on this preliminary comparison, the client decided to proceed with the design of the Vacuum Kettle separation process.

Using a combination of CHEMCAD process simulation software and Excel workbook models, PROCESS developed a comprehensive detailed mass and energy balance for the process that defined the flow rates, compositions, temperatures, pressures, and physical/chemical properties for the major process and utility streams.

PROCESS utilized the mass and energy balance information generated during the process simulation and prepared detailed Process Flow Diagrams (PFDs) to depict the primary unit operations and major process and utility streams.  Mass and energy balance stream summaries were located at the bottom of the PFDs that illustrated all required design characteristics including the temperatures, pressures, flows, and physical/chemical properties for each stream.  Major process control functions were included on the PFD.  Preliminary pipe sizing was also included as part of the CHEMCAD simulation.

PROCESS prepared preliminary equipment specifications for the new major process equipment items and key process instruments.  Instrument duty specifications for key process instruments were also developed.

The above information was provided to a detail design firm in Canada.  The design firm provided semi-detailed capital cost estimates for the client’s process.  PROCESS continued to work with the detail design company during this phase of the project to provide requested process details and to ensure the integrity of the process design was maintained.

Later, the client determined that initial constraints on the maximum allowable temperature for the Invert Oil product that dictated that the hexane–oil separation be carried out under vacuum conditions could be relaxed to the point where a separation under pressure conditions was feasible.  This led to a second CHEMCAD simulation and associated process design developed by PROCESS for a Packed Tower distillation system to accomplish the hexane–oil separation.  As before, the process information was provided to the detail design firm for capital cost estimation and PROCESS worked with the detail design company to provide requested process details and to ensure the integrity of the process design.


Industry Type

  • Oil & Gas Exploration
  • Drilling Fluids Manufacturing and Recovery

Utilized Skills

  • Process design (FEL-2)

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