Process cooling is often the single largest contributor to batch cycle time. Reducing batch cycle time can often result in lower manufacturing costs and greater profits. Since the process cooling segment is such a big contributor, a percentage decrease in this segment will have a significant impact on the overall cycle time. In our recently published Batch Processing Guidance, I discuss multiple strategies for decreasing process cooling time. Today, I would like to dig a little deeper into improving the jacket side heat transfer performance.
Typical Process Cooling Design
Process cooling typically is provided from a central cooling system that can be tower water, chilled water, glycol or another coolant. Very simply, the coolant enters at one temperature and leaves at a higher temperature. The quantity of coolant that flows through the jacket of the vessel is dependent upon the pressure between the supply and return lines – typically fixed by the characteristics of the utility system. This design works well when the temperature difference between the coolant supply and batch temperature is large (> 30C). For smaller temperature differences, the thermal resistance in the jacket starts to be a significant factor.
The process dynamics of every system are different. The physical configuration of a system and the thermal goals of the process need to be considered. As a generalization, the lower the temperature difference between the batch and the coolant, the less effective a typical process cooling design will be in removing heat from the system.
Enhanced Process Cooling Design
Typical Cooling System
The enhanced process cooling design compensates for the low supply of coolant. It dramatically increases the velocity of the coolant in the jacket. This increased flow velocity will improve the overall heat transfer capability of the system. Better heat transfer means reduced overall process cooling time. It is important to note the following:
- The circulation pump is typically a very low pressure, low hp pump and is designed only to compensate for the flow resistance in the vessel jacket at the higher flow rates. Small in-line pumps are ideal for this purpose.
- When properly designed, the observed result will be an increase in the outlet temperature of the return coolant relative to the typical design.
- The enhanced process cooling design is most effective during the later stages of the cooling cycle.
- Check valves and other controls may be required for the efficient operation of the system.
A High-ROI Opportunity
We think that many batch processing systems could benefit from this very minor modification.
This system could be installed during a short shutdown. At it’s simplest, it would include a commercial circulation pump, a manual thermostat and some minor piping modifications. If you need some assistance in making this work for your system, feel free to contact me at john.messer@analogyllc.com.
For more tips, tricks and strategies to improve the operation of your batch process, download our FREE Batch Processing Guidance https://analogyllc.lpages.co/turbocharge-your-batch-process/
Have a great day!
John