RETRACTABLE PACKING

• Greatly Reduce Steam Leakage
• Improve Heat Rate 1-2%
• Burn Less Coal - Reducing Emissions - SAVING MONEY
• Increase KW Output 2-3%
• Eliminate Rubs at Start-Up
• No Modifications to Rotor or Packing Holder
• Field Proven in Over 600 Turbines

Retractable Packing was designed to reduce steam seal leakage and improve turbine efficiency.

The flat spring normally located behind the conventional packing ring segments have been replaced with coil springs located in holes machined in the butts of the center packing segments. The coil springs cause packing segments to move radially away from the shaft, taking up the amount of space between the back side of the packing ring and the packing holder. This space is normally .125" and when combined with the design radial clearance of .025" (OEM normal), the clearance between the packing teeth and the rotating shaft totals .150". This avoids packing rubs at or below the critical, due to vibration or thermal gradients associated with cold start-ups.

In addition, a slot has been machined on the back side of the packing ring at the center of each segment to allow upstream pressure behind the packing segments. As steam flow increases, the steam pressure behind the packing ring overcomes the spring and friction forces, causing the packing to close. The packing segments will then be operating with design clearance, having avoided rubs during start-up.

SENSITIZED PACKING

• Greatly Reduce Steam Leakage
• Improve Heat Rate 1-2%
• Burn Less Coal - Reducing Emissions - SAVING MONEY
• Increase KW Output 2-3%
• Can Be Used in ANY Location
• Reduced Packing Tooth Wear by 50%
• No Modifications to Rotor or Packing Holder
• Reduced Rotor Heating from Rubbing 5:1
• Field Proven in U.S. and Canada

This patented application allows the packing ring to accommodate the specific pressures and forces that exist on each packing segment by floating on springs which are "sensitized".

The upper packing ring segments are isolated from the lower segments to minimize necessary spring forces. Sensitized Packing Rings have the ability to provide a seal with reduced rubbing forces when compared to conventional rings. As a result, leakage and heat generated from rubbing can be reduced to less than 1/5" of that experienced in original designs, resulting in improved efficiency.

The introduction of Retractable Packing eased the problems of temporarily bowed rotors during start-up conditions, thus greatly reducing the occurrence of tip seal and packing ring tooth wear. Sensitized Packing produces similar results but with added advantages.

Sensitized Packing can be applied to any areas presently utilizing conventional packing ring designs. Recent installations in boiler feed pump turbines have proven to be effective in eliminating previously experienced end packing leakage and condensation into the bearing oil.