Tuesday, July 24, 2007
Should we install Forced Draft (FD) Air Cooler or Induced Draft (ID) Air Cooler on an offshore platform ?
Induced draft fan is generally prefer from air cooling perspective as forced generally more prone to hot air recirculation. However, this potential expose maintenance group to hot air and huge resistance given by the operation & maintenace team.
Benefits / advantages of using forced draught fan are :
- Maintainability - Forced draught fan easier to maintain, better accessibility and handling of fans & drive-assembly
- Power - Lower power consumption for forced draught fan
- Vibration - Less prone to vibration due to shorter fan shaft employed for forced draught fan
- Cost - Lower initial cost and more economical to maintain for forced draught fan
- Space - Forced draught fan require less space, especially lesser plot width
However, disadvantages of using forced draught fan are :
- Inlet air distribution - Less uniform air distribution and higher tendencies of hot air recirculation
- Noise - Forced draught fan has higher noise level
- Control - Less controllability as compare to Induced draft fan
Conclusion from the debate is FORCED DRAFT fan will be installed only after Hot Air Recirculation Analysis using CFD has been carried out to definitely confirm air temperature will not accumulate and affect the air cooler performance.
Further reading :
- Hot Air Recirculation by Air Coolers (3.6MB)A.Y. Gunter and K.V. Shipes, Hudson Products Corp., Sugar Land, Texas