wet compress

TIAC or Wet Compression: Which is Right for Your Application?

Ambient conditions have a significant impact on the operation of natural gas power plants. This is largely due to the fact that as temperature and humidity rise, air becomes less dense and mass flow rate through combustion turbines decreases.

Inlet cooling has become a popular method for boosting power output by lowering the temperature of air before it enters the turbine’s compressor. Plant operators today have the option of using any number of cooling/chilling techniques for reducing air inlet temperature – two of the most common of which are turbine inlet air chilling (TIAC) and wet compression.

Both TIAC and wet compression offer distinct advantages that make them more or less suitable for use depending on the specific needs of the facility. Understanding what those advantages are is essential to making the right decision when choosing which method to employ, thus ensuring optimal use of capital budgets.

The purpose of this blog is to help operators make that decision by providing an overview of both methodologies. 


Supplementary “Duct” Firing for Combined Cycle Power Plants & How it Compares to TIAC

While both Supplementary or Duct Firing and Turbine Inlet Air Chilling (TIAC) are solutions to offset the megawatt output degradation of gas turbines when ambient temperatures rise, the two technologies take very different approaches.  With TIAC, the combustion gas turbine inlet air is chilled. In the case of duct firing, injection of fuel is utilized to increase the temperature and mass flow rate of the exhaust gases.

Rather than competing, the two technologies – duct firing and turbine inlet cooling – can actually complement each other when used correctly.

For maximum power output, power plant owners can utilizing the reliable power augmentation provided by TIAC, and balance the requirements with duct firing.  This scenario allows them to produce the required power at the lowest possible heat rate.

However, the combination of TIAC with Duct Firing is rare – most owners choose one solution over the other. Let’s look at how Duct Firing works.


Evaporative Cooling or Mechanical Chilling: Which Works Best in Power Production?

If you’re outside working on a hot summer day, it’s inevitable that moisture will appear on your brow.  A dry breeze evaporates the perspiration and cools down your body. This is nature’s way of keeping you productive because no one works efficiently when they are too hot. Nature’s cooling technique is effective — as far as it goes. But clearly, you’ll cool down more in an air conditioned room than by relying on outdoor breezes. This is especially true when it is humid, since damp air cannot absorb as much moisture as dry air.

So AC is more effective and predictable than nature to remove the sweat off your brow on a hot August day.

How does this apply to power generation? Like us, the gas turbines used in power plants operate less efficiently when the air is too hot.

And interestingly, the two most common technologies for cooling power plants — evaporative cooling and mechanical chilling – mirror the way we cool down our bodies. They even share similar pros and cons.

Here is a more detailed description of the two cooling technologies, as they are used in power production.