How the 7Extend upgrade package helps GE Customers

Here’s how GE Gas Power has helped fleet operators with solutions custom to their 7E plant operations, bringing restored turbines into the next generation of profitable operation.


Retrofittable casings enhance 7B turbine performance

A GE Gas Power customer, a major natural gas power station in south Texas, had experienced turbine and exhaust casing cracks, as well as out of roundness issues. The customer experienced downtime and costly repairs from out of roundness issues in its peaking operation, with 100 to 200 starts per year. Operators observed cracking, which initiated and propagated. Despite appropriate maintenance—drill relief holes to stop propagation—the cracks continued.

The costs related to downtime and operational maintenance were mounting, without resolving the issue. In response to these concerns, which are driven by cyclic duty heat cycles and age, the customer had upgraded a 7B with a 7E turbine end.

More recently, after a competitive search for the best solution, GE products were selected to replace the exhaust frame assembly (casing plus diffuser) on two units with 7EA configuration exhaust frame assemblies, as well as replace the turbine shell on one of those units. The unit with turbine shell replacement recovered an additional 3-4 MW when compared to the sister unit.


Recovering from performance degradation

Our well-known industrial cogeneration customer had a 7E turbine installed at their site in October 1982 to generate energy and steam for the process. In the ensuing 40 years, casings experienced degradation, such as cracking, corrosion, and other age-related issues.

The customer’s goal is to extend the functional life of their units for up to 20 years or more, and GE Gas Power extended its working relationship with them to help meet this goal.  After a comprehensive selection process, GE Gas Power will provide all new 7E casings, a new set of stator vanes and a refurbished rotor, scheduled for installation in spring 2023.


7EA upgrades are retrofittable and reliable

Operating a 600 MW cogeneration facility in Channelview, TX, our customer provides steam and electricity for industrial chemical processes. The facility ran five 7EA turbine units with long service tenures. These units had logged over 250K hours and had already had life extension maintenance. The turbine shells had reached the end of useful life. 

After considering refurbishing of the 71E old design exhaust frame assembly, the customer selected an upgrade to an available 7EA parts exhaust frame, making minor necessary modifications.  

The new 71EA exhaust frame assembly consists of exhaust frame, an inner forward diffuser, an outer forward diffuser, flex seals and an aft diffuser. Also integrated are exhaust frame cooling piping modification; and the cooling and sealing air piping arrangement for load tunnel fire protection

The upgraded exhaust frame will upgrade flex seals and Inconel gaskets to reduce leakage, as well as improve cooling inside the load tunnel and into the #3 bearing, better the diffuser configuration to reduce stresses, and enhance airfoil configuration to increase reliability.

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