Case Study 3 - Turbine Division: Marine Gas Turbine

Turbine Division: Marine Gas Turbine

Application: Marine Gas Turbine Generator Enclosure Ventilation System Inlet Silencer.
Challenge: To meet the customer's noise reduction requirement with very little available space for the noise attenuation equipment.

  Details: The customer's 22 MW marine drive gas turbine generator package installed location deep within an oceangoing cruise ship allowed minimal room for the accessory equipment necessary to operate the machine.  The turbine enclosure required an ambient air volumetric flow rate of 21,500 cfm to maintain the desirable surrounding temperature for the turbine and other equipment operating in the enclosure.  Two centrifugal fans (one operating, the other an installed back-up) located on the roof of the enclosure provided this airflow.  Based on the customer's available space and predetermined equipment layout, the ventilation system inlet silencer needed to do more than just provide the specified noise insertion loss.  The layout required the silencer to direct the airflow over the top of the fans and turn it 180 degrees into the fans' horizontal inlets.

  VAW Systems' Solution:  Utilizing and combining two VAW Systems' silencer designs, the Model EIB Elbow Silencer and the Model RSB Rectangular Inlet Box Silencer, a custom ventilation silencer package was developed to meet the customer's requirements.  The Model EIB Elbow Silencer design received the airflow from the turbine system's main air intake duct, directed it horizontally across the top of the fans, and turned it vertically downwards while providing a portion of the desired noise insertion loss.  The Model RSB Rectangular Inlet Box Silencer design then received this airflow and turned it horizontally into the two fans' circular inlets at the same time as it provided the balance of the noise insertion loss.  The final silencer package design incorporated one rectangular inlet for attachment to the customer's air intake duct and two circular outlets for attachment to the ventilation fans.  This allowed for just one silencer system to be in service regardless of which fan was operating, minimizing the physical space needed for this noise attenuation equipment.  The customer installed back draft dampers at the two fans' outlets to insure this common inlet silencer layout did not allow recirculation ("short-circuiting") of the ventilation airflow by being drawn backwards though the fan in back-up standby mode by the fan in operation mode.

This VAW Systems' silencer design is now sailing the high seas aboard a number of ships operated by a world renowned cruise line.