Loss-in-weight feeding in continuous powder manufacturing.

摘要

Processes involving granular material handling are found in many industries, such as pharmaceutical, chemical, catalyst, and food. Significant differences are observed, both between materials as well as between handling methods. Often, special equipment has been developed to monitor, control, and feed these widely varied materials in order to enable the end user to continuously feed or dose the raw powder material so that it can be continuously processed, which has many advantages over batch processing.;To address the difficulties of feeding granular materials, powder feeders are equipped with a variety of tooling that can be used for various rates and powders. Unfortunately most of the sizing and performance knowledge is internal to the feeding equipment manufacturers and is not generally available to the end-user.;In this work, a method for evaluating feeding performance was developed, which allowed for testing that was independent of the type of feeder being evaluated. This method was applied to various feeders to characterize the feeders for the feeding of various powders. In addition, the effects of hopper refilling were quantified and investigated. Finally, the downstream effects were simulated.;For each powder, the fluctuations caused during normal steady state feeding were minimized through tooling and feeder selection. The effects of refill were found to be considerably more significant than the fluctuations associated with steady state feeding. However, optimized refill schedules, easily reduced the deviations to more manageable levels.;In continuous manufacturing systems, the feeders are a potential high risk to content uniformity. The implications of this are investigated from a overarching view of a pharmaceutical direct compression system with a specific focus on regulatory compliance and product quality. Regulatory compliance requires batch definition and raw material traceability, and solutions to both were investigated. The presented options for batch definition are based on the residence time distribution (RTD) of the system, which describes the dispersion of material across the interface between "batches". Raw material traceability was similarly investigated utilizing residence time distribution as a tool.