Metal Bellows-Type Seal

With the TDGS, the company presents a high-efficiency gas-lubricated seal optimally sutied for use in single-stage steam turbines in the petrochemical and chemical industries. Wear-free operating and extremely low leakage rates put the TDGS in a class of its own.

The sealing face of the rotating seat is machined with three-dimensional V-grooves. With no sharp edges at the groove exit where dirt particles can accumulate, all particles are drawn through the sealing gap. Dirt deposits are prevented and a self-cleaning effect thus achieved. Temperatures of up to 450°C can arise in steam turbines, preventing the use of conventional sealing elements such as O-rings in the spring-loaded part of the gas seal. The company's answer to the problem is to use a metal bellows as secondary seal for the stationary seal face; this ensures interruption-free operation and guarantees the high level of reliability reached by the seal in field tests. An operating pressure limit of 25 bar and the attainable sliding velocity of 120 m/s open up an extensive range of uses in steam turbines with shaft diameters of up to 180 mm. The seal prevents the formation of dense fogging around the turbine at low external temperatures.

Advantages

• No steam condensate in the bearing oil
• Reduced temperature gradient between seal and bearing
• Greater turbine efficiency
• Conversions only call for slight alterations to the turbine or none at all
• Atomization period < 1 year

Special Features

• Stationary metal bellows
• SiC-Si/carbon graphite as the combination of face metals
• Statotherm secondary seals
• Bellows made from Inconel
• Open gas seal grooves with self-cleaning effect
• Pressure reversal permitted (vacuum mode)
• Designed as cartridge unit

Burgmann, Feodor, Dichtungswerke Gmbh & Co, Postfach 1240, Wolfratshausen, Germany 82502. Tel: 49-8171-230; Fax: 49-8171-231214.