Mixing and blending are critical to a successful pulp/paper mill operation. The mass concentration of the pulp suspensions (aka consistency) in chests must be uniform at all locations. This is typically done with open face high efficiency impellers (hydrofoils). Along with a properly sized agitator the proper chest design and feed/pump suction locations are also critical to uniform consistency. One method used to provide uniformity is the momentum method which this presentation is based on. The mathematical model for the momentum method will be presented along with guidelines for chest designs and agitator locations. A successful agitator design relies on good data and information from the mill engineer such as geometry of the chest and the process information outlining what is expected of the agitator. This presentation will describe what an agitator supplier must know to design the equipment and describe the "why" so the plant engineer can understand not only the importance of chest geometry, feed and pump suction locations, but the process information as well: stock characterization, throughput and temperature. A good understanding of the relative importance of these design factors will help the plant engineer in making decisions for optimization, retrofits and upgrades. A typical blend chest design will be used to illustrate the design steps.
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