Recirculation from pump discharge through a flow control orifice and cooler to the seal chamber.
Description
Plan 21 is like Plan 11 but with the addition of a mechanical seal cooling system
Application Notes
- Plan 11 with cooler.
- Throat bushing is used to isolate product in the seal chamber from product in the pump volute.
- Provides a cool flush to the seal to improve lubricity, reduce coking, and/or avoid fluid flashing to vapor.
- If the cooler duty is high, fouling and clogging on the water side can occur over time.
- Potential clogging on the process side if the fluid becomes too viscous at reduced temperature.
- Requires more energy usage than Plan 23 since the fluid must be continuously pumped back to discharge.
Pros:
- Dramatic seal life enhancement with proper design and operation
- Renewable filters to ensure continuous supply of clean flush liquids
- Cool flush improves seal lubricity and reduces coking
Cons:
- Clogging risk with elevated temperatures
- Higher energy usage
- Maintenance of the Seal Cooler