Evaluate and troubleshooot a polymer pellet dryer/cooler station to prevent unwanted clumping of pellets inside packaging containers during hot summer conditions.
POLYMER PELLETS DRYER/COOLER PROCESS EVALUATION AND SIMULATION
The client provides multi-discipline engineering services for the ultimate client, a chemical manufacturing facility. Process Engineering Associates, LLC (PROCESS) was subcontracted by the client to determine what should be done to improve the effectiveness of a dryer/cooler that the ultimate client uses in a process to manufacture fluoroelastomer pellets. As a final step before packaging, the pellets are routed through the dryer/cooler, which uses a combination of ambient air and air cooled by chilled water to reduce the moisture content and also lower the temperature of the pellets. During warm weather, however, the dryer/cooler is not able to cool the pellets sufficiently, which causes problems with the pellets sticking together once inside the product containers. PROCESS was asked to perform engineering analysis, including a process simulation, to predict the feasibility of supplying additional chilled water to the dryer/cooler in its existing configuration to achieve a temperature of 80-100o F for pellets leaving the unit. Should the analysis results indicate that increasing the chilled water flow would not achieve the desired effect, PROCESS was asked to provide recommendations that would achieve the 80-100o F pellet temperature during warm weather.
Using the information provided by the client, a review of the dryer/cooler unit (including a process simulation generated by PROCESS) indicated:
- The greatest factors in the ability of the dryer/cooler to cool the pellets are air/pellet contact time and air/pellet contact area. The temperature of the air entering the dryer/cooler does impact the exiting pellet temperature, but to a lesser degree than time and area.
- It is probably not feasible to achieve a lower pellet temperature by connecting chilled water to the steam coils on the existing air handlers connected to the dryer/cooler. The pressure drop of these coils would be too high to achieve the needed chilled water flow.
- The most effective means of reducing pellet temperature using the existing equipment would be to reduce the belt speed (increase residence time) and ensure that the pellets are spread out on the belt as much as possible (increase pellet/air contact area).
- If increasing residence time or better pellet distribution is not feasible, then purchasing new air coolers for additional chilled water might be the only option short of buying a new dryer/cooler.
- Further increasing the supply of chilled air to the dryer/cooler could increase the amount of moisture in the pellets, which could be detrimental to product quality. Some analysis will be required to determine the likelihood of increased pellet moisture if additional chilled air is provided for the dryer/cooler.
The client reviewed the results with the ultimate client. Additional work by PROCESS using additional dryer/cooler operating data may be required to confirm these results if the ultimate client decides to move forward with some combination of these findings.
- Polymer Manufacturing
- Process troubleshooting
- Process equipment evaluation
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