LIW CONTROL RETROFITS COMPLETED FOR TWO PE COMPOUND LINES
Melfi Technologies has completed a gravimetric feeder control retrofit at a major polyethylene resins producer. Each of the two compounding lines consists of a single main powder resin LIW screw feeder running at 30,000 pounds/hour, with four powder additive LIW feeders running at 10-150 pounds/hour.
The entire proprietary microprocessor-based control system was removed and replaced with an Allen-Bradley ControlLogix PLC performing the LIW algorithms, using Hardy Instruments Devicenet weighing modules mounted on the individual feeder to read the loadcell weight. Keeping all the field equipment on a Devicenet network ensured only a single new field cable needed to be pulled for the entire retrofit.
Downstream of the pelletizer there is weighbelt feeder to totalize the finished pellet stream. The belt feed rate is controlled by an analog level indicator in the prefeed hopper. The operator enters a level setpoint, and the PLC will control the belt speed to maintain the hopper volume.
The operator interface consists of an Allen-Bradley RSView32 local touchscreen monitor located in the control room, with a remote redundant touchscreen monitor located in the extruder panel for easy field access.
Both lines were retrofitted, commissioned and operational within a two-week time span. The feeders continue to perform well with no additional service or repair return visits by Melfi Technologies.
Gravimetric Feeder Control
LIW CONTROL RETROFITS COMPLETED FOR TWO PE COMPOUND LINES
Melfi Technologies has completed a gravimetric feeder control retrofit at a major polyethylene resins producer. Each of the two compounding lines consists of a single main powder resin LIW screw feeder running at 30,000 pounds/hour, with four powder additive LIW feeders running at 10-150 pounds/hour.
The entire proprietary microprocessor-based control system was removed and replaced with an Allen-Bradley ControlLogix PLC performing the LIW algorithms, using Hardy Instruments Devicenet weighing modules mounted on the individual feeder to read the loadcell weight. Keeping all the field equipment on a Devicenet network ensured only a single new field cable needed to be pulled for the entire retrofit.
Downstream of the pelletizer there is weighbelt feeder to totalize the finished pellet stream. The belt feed rate is controlled by an analog level indicator in the prefeed hopper. The operator enters a level setpoint, and the PLC will control the belt speed to maintain the hopper volume.
The operator interface consists of an Allen-Bradley RSView32 local touchscreen monitor located in the control room, with a remote redundant touchscreen monitor located in the extruder panel for easy field access.
Both lines were retrofitted, commissioned and operational within a two-week time span. The feeders continue to perform well with no additional service or repair return visits by Melfi Technologies.
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