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.

water air cooled

Water versus Air Cooled Chillers: Which is Best for Power Plants?

Fabrication of a modular chiller plant

To call water a hot commodity is an understatement.  From controversial water trading to desalination, a slew of efforts are underway to solve water scarcity issues in many regions of the world.  Some, like the massive undertaking by Israel to reuse wastewater and desalinate water from the Mediterranean Sea, are having an impact.  But as population and urbanization continues to grow worldwide, so does water consumption, and, naturally energy use.

Water and energy are closely tied. Consider that thermoelectric power plants – which currently provide the vast majority of US electricity — consume a lot of water.  In fact, the power industry is one of the largest water users in the United States.

Presently, in the US, coal plants are being displaced by natural gas plants.  However, gas turbine efficiency is the lowest when the demand for power is the highest, during hot summer months. To offset this negative effect of high ambient temperature, gas turbine inlet air can be cooled via mechanical chillers.


Minimizing Lifecycle Costs for Turbine Inlet Air Chilling: How to Do it and Why it’s Important

In an ideal world, the most efficient equipment would also cost the least to buy and install. But in the real world that’s usually not the case.

Equipment often runs more efficiently because it’s made from higher grade materials. Higher grade materials cost more.

Anyone who has priced home air conditioning systems is aware of this. But as Energy Star labels often reveal, lower electric bills offset the higher cost to purchase the AC system over time. The efficiency pays off by making the house cheaper to operate.

A similar principle applies to turbine inlet air chilling (TIAC) systems for power plants, but on a much larger financial scale. Lower capital costs (capex) may mean higher operating expenses (opex). That’s why it’s important to consider the total lifecycle costs — and how to minimize them — when investing in a TIAC system.