Polymer Processing Technology in 2018 and Beyond

The polymer industry uses many types of equipment and technologies to process solids, liquids and gases. Here, our expert speakers focus on direct and indirect drying technologies used for heat transfer in polymer solids processing.

A common direct heat transfer application is the removal of water from a heat sensitive material using hot air as the heat transfer medium. Direct heat transfer equipment uses evaporative cooling to prevent degradation of the process material upon drying. In contrast, indirect heat transfer is typically used in drying applications where the solvent is not water (i.e. flammable organic solvent) and utility use of nitrogen to produce an inert environment needs to be minimized.

Typically, direct thermal technologies have a lower CAPEX cost and higher utility cost than indirect thermal technologies. The long-term utility cost can impact the payback of a project to such a degree that the utility usage of the direct thermal equipment will outweigh the larger initial CAPEX cost of the indirect thermal equipment.

The devolatilization of polymers is a crucial part of almost every polymer production process and its importance is often overlooked. Volatiles generally consist of un-reacted monomers, hydrocarbon solvents, and/or water. Successful operation of downstream equipment (e.g. extrusion) often requires devolatilization. The volatiles can be removed during extrusion or post extrusion, however, the most cost-effective processing technique is to devolatilize prior to the polymer going into a molten phase because devolatilization is a function of specific surface area. Polymer material in granular form has a large specific surface area relative to polymer material that has passed through a molten phase.

Bepex has found that the most effective means of devolatilization is a two-stage operation: indirect heating then inert gas stripping. When the polymer discharges from the reaction system, the polymer, un-reacted monomers, and solvents are heated indirectly by steam or hot liquid to an optimum processing temperature in low concentration or complete absence of an inert gas. The residence time in this stage is long enough to approach the equilibrium concentration in the saturated atmosphere. The low concentration of inert gas will allow the volatiles to be recycled directly to the reaction system without treatment.  In the second stage of the operation, an inert gas, such as nitrogen, removes the remaining volatiles to a level acceptable for extrusion. This operation is typically conducted in a purge bin; the inert gas is passed counter-current to the downward flowing granules producing a volatiles-stripping action.

Obtaining large quantities of representative material for pilot trials can be expensive and presents a challenge to process scale up. To overcome this challenge, Bepex has developed methods to analyze the critical properties of polymers on a bench scale and use them to model a commercial system. This method can also be used to optimize the performance of an existing system with new formulations.

Speakers

Isaac Willard, Thermal Application Engineer, Bepex International, LLC

Isaac Willard has nearly one year of experience in the industrial process design industry and is responsible for the process design of full-scale thermal technology offerings. Recently, Isaac has contributed to the design of resin drying and volatile extraction processes which showcase the versatility of Bepex International’s rotary equipment technology.

Isaac was born in St. Paul, Minnesota and holds a B.Ch.E and MSME from the University of Minnesota. Isaac is an expert in Rheology and Particle Mechanics with experience in polymer design and processing as well as small particle processing, characterization, and solids and gas phase material interactions.

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Scott Halvorsen, Director of Thermal Technology, Bepex International, LLC

Scott Halvorsen has over 35 years of experience with Bepex and other industrial process equipment suppliers. For the last 20 years, Scott has focused on various thermal equipment technologies and their applications in food, chemical, polymer, mineral and related industries. Scott has authored, co-authored, and contributed to several industry papers, patents, and presentations worldwide. Scott holds a BSME from the University of Minnesota and has taken several advanced engineering and technology classes as well as teaching food technology classes at Texas A&M. Scott is a member of AIChE and ACS.

Scott started in the Bepex Process Technology Center and worked on a multitude of process technologies including agglomeration and compaction, mixing, size reduction, various thermal technologies, and a variety of industrial process auxiliary technologies. Scott’s prior positions at Bepex include Lab Engineer, Application Engineer, Product Manager, and International Sales Director.

 

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