Taurus Group 60 - Manual (Page 61)

Turbomachinery Package Specification Taurus 60 Compressor Set and Mechanical Drive
14 Exhaust System
14.1 General Description
The exhaust system typically consists of all components installed downstream of the
engine exhaust bellows expansion joint, including silencers, expansion joints and ducting,
that are necessary to ensure a smooth flow of exhaust gas from the engine. The exhaust
duct system must be terminated in a manner that precludes recirculation of exhaust
products through the engine air inlet or oil cooler. Exhaust considerations include the
relative height of the exhaust duct above the air inlet, building roof design, direction of
prevailing winds, and the proximity of adjacent structures. The importance of having an
exhaust system properly designed cannot be overemphasized. When exhaust silencing is
required, provisions must be made to adequately mount and support the equipment and
limit the exhaust silencer pressure loss, with no loads transmitted to the turbine exhaust.
Exhaust systems should be designed to meet the following requirements:
• Where two or more units exhaust into a common header, such as used for heat
recovery equipment, provisions must be made to prevent hot gas from flowing
into the non-operating unit (common exhaust ducting is not recommended).
• Final termination of ducting must not allow exhaust gas to be drawn into the
gas turbine inlet.
• Capability to purge the complete exhaust system prior to gas turbine lightoff.
For short simple exhaust systems, purging should be designed to accomplish
three air volume changes. For large complex exhaust systems, purging should
be designed to accomplish five air volume changes either through gas turbine
cranking or supplementary exhaust blowers.
14.1.1 Exhaust Silencer
This exhaust silencer is designed for use with radial exhaust gas turbines. A support
structure and ducting can be provided to support the exhaust silencer assembly. Brackets
are available for mounting the silencer in a vertical or horizontal position. Figure 24
shows a typical Taurus 60 mechanical drive with a radial exhaust silencer.
14.2 Turbine Exhaust Heat Recovery System
High thermal efficiencies can be obtained by using the gas turbine exhaust heat energy.
There are several methods for using the exhaust heat and attaining greater than 80% fuel
utilization. The methods used and the efficiencies achieved are primarily dependent on
the type of application. The most common uses are:
1. Producing steam with a heat recovery steam generator (HRSG) or heating a
process fluid with a heat recovery fluid heater.
2. Using the gas turbine exhaust as a source of preheated combustion air in a
boiler or furnace (the gas turbine exhaust contains 15-18% oxygen).
3. Using the gas turbine exhaust directly for a drying or heating process in which
high temperature air is necessary. A mixture of gas turbine exhaust and fresh air
can be used in a reduced air temperature process. An air-to-air heat exchanger
is required when the process involves any products in the human food chain.
Solar can design and provide a complete exhaust heat recovery system to meet specific
application requirements. The system must be designed to minimize the backpressure
imposed on the gas turbine exhaust and provide a smooth flow transition into the exhaust
heat recovery device.
© 2009 Solar Turbines Incorporated. All rights reserved. TPS60CSMD/309
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