Upstream Gas Turbine Inlet Fogging System

Up to 25% Power Boost – Even in Humid Climates

Upstream fogging is an inlet air cooling technique for gas turbines that cools the air stream before it enters the air filters. Upstream fogging is especially ideal when filter house design constraints or long-term service agreements restrict installation of the fog nozzles inside the air intake duct.

Upstream fogging also pre-filters the air. Fog spray that does not evaporate is collected on a droplet eliminator or on water resistant pre-filters. The drain water flow carries away dust that would otherwise accumulate on the pre-filters. Drain water can be treated and reused. By installing MeeFog nozzles ahead of the inlet filters, you gain a flexible, rapid power boost.

With over 1,000 installations over the past 30 years, Mee Industries is the trusted leader in inlet air fogging – delivering unmatched reliability, performance, and long-term value.

MeeFog Upstream Systems Include:

High-efficiency fog nozzles with stainless steel construction
Droplet eliminators or coalescer filters for effective moisture control
Pre-engineered pump skids with PLC controls
Integration with your DCS

Challenge

Plant operators must reduce gas turbine power loss in high temperatures, but LTSA restrictions and filter house design limits prevent modifications to the intake duct.

Solution

MeeFog installs a high-efficiency upstream gas turbine inlet fogging system ahead of the air filters, delivering evaporative cooling without modifying internal ductwork.

Results

Facilities can boost power generation by up to 25%. Upstream fogging also acts as a pre-filter, capturing dust, and droplet eliminators drain excess water, helping extend the life of existing pre-filters.

MeeFog GT Upstream Fogging Installation Diagram

Schematic of a fog-based evaporative cooling system for a gas turbine, showing water softening, high-pressure fogging, filtration, and air intake flow.

System Overview

Power Boost

MeeFog System Benefits

Fog cooling increases output by 20% or more.
Overspray fogging provides additional boost.
Reduced NOx emissions up to 30%.
Improved fuel economy.
Reduced CO2 per kW of power.
Robust equipment & proven technology.
Guaranteed results!

Droplet Comparison

Small droplets have a larger surface to volume ratio compared to larger droplets. This allows them to evaporate much more rapidly than larger droplets.

Want Proof?

We’ll gladly supply a detailed power recovery report for your existing gas turbines including:

Installed MeeFog system cost.
Predicted MW-hr gain per year.
Fuel savings.

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Featured Case Study

Industrial air intake system at a gas turbine facility featuring upstream fogging installation

Upstream Fogging Is Making a Comeback for Gas Turbines

Placing fogging systems upstream of filters helps plant operators improve air filter life, reduce maintenance costs, and boost turbine performance. MeeFog upstream systems deliver powerful cooling while capturing airborne dust, protecting critical components, and extending equipment life. Partnering with Mee Industries can help increase power output, lower lifecycle costs, and ensure that operations remain efficient and reliable for years to come.

Read More View all Gas Turbine Inlet Air Cooling Case Studies

MeeFog Nozzle

Each MeeFog impaction-pin nozzle is made from high-grade stainless steel. The standard nozzle features a 0.006 inch (150 micrometer) diameter orifice which produces billions of ultra-fine droplets per second. At an operating pressure of 2000 psi, the average droplet size is below 10 micrometers, or one tenth the diameter of a single strand of human hair. The resulting fog provides fast evaporation and amazing special effects.

Features:

High-grade, precision-machined type 316 stainless steel construction.
Super smooth orifice, low-pressure drop, 98% efficiency.
Cylinder type filter with radius end for efficient nozzle operation.
1/8″ NPT tapered fitting.
O-Ring seal at the base of the nozzle.

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FAQs About Upstream Gas Turbine Inlet Fogging System

What happens to overspray or non-evaporated water upstream of the filters?

Upstream systems manage unevaporated water with a fog droplet eliminator or waterproof filters, preventing bulk moisture carryover into the filtration section. A drain water flow of ~10–20% can also be routed back to a raw water tank (in applicable designs).

How much power boost can I expect from a MeeFog upstream inlet fogging system?

A MeeFog upstream fogging system can deliver up to 25% power boost, depending on ambient temperature, humidity, and turbine model. For an aeroderivative turbine in a humid climate, the power boost can reach 30%. For a large-frame industrial turbine, the boost is typically around 8% in a humid climate. Power boosts can be more in hot, dry climates.

Does upstream inlet fog work in humid climates?

Yes, upstream inlet fogging still gives a significant power boost even in humid climates. The system evaporates very small water droplets to move the air closer to saturation, increasing air density and turbine output by 10% or more, even in very humid regions such as Southeast Asia.

What impact does upstream fogging have on turbine components and compressor life?

Since no water droplets are introduced downstream of the filters, there is no possibility of compressor blade erosion from water impingement and no risk of compressor fouling. The turbine operates as it normally does during high humidity. Fogging downstream of the air filters requires demin water to avoid the accumulation of mineral deposits on the compressor blades. Fogging upstream can be done with softened tap wate

What is the effect of placing fog nozzles upstream of the air filters on filter life and maintenance?

The fog itself is a good dust collector. About 10% of the fog water doesn’t evaporate before the mist eliminator or water-resistant filters, so it is drained away as liquid water. Drain water can carry dirt and dust away with it, thereby reducing the dirt load on the air filters themselves. The drain water can be treated and reused.

What water quality does upstream fogging system require?

Since the water does not enter the gas turbine, it’s possible to use raw water. If the raw water has high mineral content, it may be desirable to soften it or to treat it with reverse osmosis. Mee Industries designs and builds water treatment systems to provide a cost-effective solution.

Can existing gas turbines be retrofitted with upstream fogging systems without major modifications?

Yes. The MeeFog system’s modular design makes it easy to retrofit existing gas turbines. In some cases, no modification other than installing the fog nozzle lines is required. The MeeFog system provides higher gas turbine power output, improves heat rate, and reduces NOx, all with a relatively low capital cost and a low parasitic load compared with other power-augmentation methods.

What is the typical return on investment (ROI) or payback period for upstream inlet air fogging?

The return on investment depends on many factors, but it is typically 1 year or less and likely never more than 2 years. Please get in touch with us to discuss your details, and our team will share a quote. You can also request a quote directly online.