A Commercially Available Continuous Bench Scale Polyolefins Pilot Plant

The Xytel-Oakwood Continuous Bench Scale Unit (CBSU) is a computer controlled, modular pilot plant offered as a turnkey system from Xytel Corporation in collaboration with Oakwood Consulting. The CBSU was specifically developed by Xytel and Oakwood as a means for Polyolefins researchers to obtain more timely and cost effective data and resin samples for commercial evaluation. The heart of the system is two continuously operating 10-Liter polymerization reactors in series with associated slurry and powder transfer systems. The reactors are chosen from two designs: Liquid Slurry CSTR or Continuous Stirred Gas Phase. The basic configuration with two Reactors is shown in Figure 2. Other configurations are possible.

The CBSU unit was designed in part using a detailed polymerization kinetic model contained in a custom user Fortran subroutine within the Aspen PlusR process simulator. The composition and conditions of all important streams were determined at steady state. The Aspen simulation also provided an accurate heat balance for key parts of the unit. The CBSU unit is designed so that the user can obtain high-accuracy material balances during a run campaign -- and provide a comparison with the material balances from the Aspen simulations (an aid to verify catalyst consumption).

The system's various components of vessels, pumps, reactors, instruments, automated valves, etc. are conveniently mounted on a single painted steel frame, or "skid", with an open threedimensional architecture for ease of operation and maintenance. The process skid occupies a footprint smaller than eleven feet in length and five feet in depth. The maximum height is eleven feet. The system's electrical design and components are installed to meet the requirements of a Class 1, Division 2, Group CD area.

The process skid contains all of the subsystems, or modules, necessary to control and feed reactants and catalysts, control the reaction parameters, and transfer and purge product. The design incorporates proprietary technologies developed by Oakwood and Xytel to allow continuous and automatic lined-out operation to produce nominally 2 to 5 Kg/Hr of resins. Some key features are highly accurate and reliable catalyst metering, choice of two reactors in series (liquid slurry and/or gas phase), reaction composition and variables control, reliable powder transfer, and fully automated operation.

The process system is automatically controlled and data logged by a Honeywell 9000 Loop and Logic Controller with SCAN 3000 software in a Windows environment. The operator interface is a Pentium-based PC with the SCAN 3000 software. Xytel configures the control system and user interface screens to provide turnkey operation.