Located in Houston Texas, GE Aero Energy is a service provider and producer for aero-derivative turbines with marine and commercial applications.
“With a tradition built on the world’s most trusted jet engines, GE’s aeroderivative gas turbines offer power output ranging from 18 to 100 MW and the ability to utilize a variety of fuels, From fast starts and load following to get on the grid quickly, to high availability and reliability to keep units online, we tailor products and services to meet our customer demands.”
Business Problem
GE was supplying a turbine package to be used on a newly designed LNG-fuelled passenger ferry and required a turbine enclosure and air-supply plenum. Commonly plenums and enclosures have heavy steel construction and are not optimal with respect to weight. Changing the structural steel and plates to aluminum could reduce its weight and potentially meet the end-user requirements.
Technical Problem
A unique set of primary design inputs and criteria for the project were as follows:
Lightweight aluminum design.
DNV certification.
Design for ship loads, transportation, and lifting.
Must comply with all GE technical specifications.
Design interfaces between steel and aluminum connections.
Use Computational fluid dynamics (CFD) to ensure a safe design.
Fully detailed fabrication drawings
Various interested parties, including the end-user, fabricator and suppliers, were scattered across the globe and therefore remote meetings were required which Innovex often hosted. The presentation of our 3D CAD modeling was key to facilitating productive conversations during design development and the fabrication process.
Solution
High strength structural aluminum sections were selected for reinforcing the relatively thin exterior plates. In an effort to keep weight down, the structural design was optimized to reduce material usage as far as possible while maintaining an acceptable factor of safety to yield. Careful consideration had to be given to the post-weld strength behaviour of tempered aluminum. The structural design was done in conjunction with CFD analysis used to verify that adequate air flow would exists through the plenum and enclosure to avoid high-temperature locations and to dilute gas concentrations in the event of a gas leak.
Flow trajectories and heat profiles on turbine and back wall developed using CFD
Working with the international certification body Det Norske Veritas (DNV), the enclosure and plenum obtained a certified design. Several design choices helped to ensure certification such a using off-the-shelf certified components as well as submitting various approval documents including FEA reports confirming the overpressure design requirement, and drawings detailing the insulation system which is critical to fire protection After completing the design stage, Innovex regularly visited site locations during fabrication and installation. Meeting the technical specifications provided from GE was accomplished through constant communication and a thorough understanding of all project requirements.
Depiction of natural gasleak to confirm that ventilation meets explosive limit criteria
Galvanic corrosion was a major concern due to having dissimilar metals in an environment surrounded by seawater. In order to prevent the aluminum from quickly corroding, various seal designs were used between all dissimilar metal connections to ensure a reliable of separation.
The design of the custom enclosure and plenum was a challenge, due to its large set of design requirements, but one that Innovex was fully committed to and able to handle. We are proud to have been involved with the development of a key component of the world`s fastest ship of its kind.
