Inline Recovery of Defect Product from Continuous-process Production Line Improves Line Yield and Eliminates Material Waste
The extreme complexity of startup events for this continuous-process production operation, and the plant-wide repercussions caused even by planned stop times, make any downtime, other than the annual plant shutdown, inordinately costly and therefore unacceptable. Recovery of reject product generated during changeovers or adjustments must be done while the line continues to run at production rate.
Previous methods of recovering the reject product proved incapable of consistently keeping pace with the high volume of product and the extended duration of the loss events. Physical restrictions of the plant layout, including its ceiling height and work area accessibility, further complicated reclamation efforts. In cooperation with the project owner’s architecture, engineering, and construction (AEC) firm, NBE led the on-site application analysis within the framework of engineered-to-application project (ETA) project delivery. Based on findings from the application analysis, and subsequent process flow diagramming and fullstream modeling by NBE, the project scope was accepted. Essential design criteria for the project included: ensuring sufficient product throughput capacity at all stages of the recovery and reclaim sequence, and building recovery-stage systems to clean-in-place (CIP) specifications. Feasibility tests, run at the NBE Innovation Center, and attended by the project owner and AEC, confirmed the designed rate for the project well exceeds actual production rate. The CIP design developments, engineered and integrated by NBE into the project, enhanced product safety conditions throughout the project. The NBE controls and automation practice designed, engineered, and integrated automation into the project’s central controls architecture that automatically initiates inline operations to divert reject product to reclamation, based on input from upstream process data. When reclamation events occur, diverter gates re-direct product from the production conveyor into the receiving hopper. A high-rate, high-capacity, solid-core screw conveyor transfers diverted product from the hopper to the milling operation where the product is milled to uniform size. Milled product is conveyed to the NBE bulk bag filling system from the mill. Recovered product is bulk packaged and staged to be reclaimed as process material in other of the project owner’s operations.
Following the successful completion of equipment-specific factory acceptance tests (FATs), NBE disassembled and prepared the project equipment for installation using modular construction methods at the production facility. Despite plant layout restrictions and the need to install the project during production line operation, the NBE installation team was able to fully integrate the project and perform start-up and commissioning with only minor, pre-planned effect to production operations. The process contributions of the NBE engineered-to-application product recovery project are many. Material loss, previously the result of defect product volume exceeding recovery system capacity, has been eliminated. The increase in recovery and reclamation effectiveness has helped to improve raw material procurement efficiencies and line yield. CIP project design reduces cleaning time and works to improve labor safety during maintenance events.