Gas turbine air intake
The air at the turbine inlet sets its output. Dust settles on the compressor blades, efficiency drops, fuel consumption rises and washes become more frequent. The job of the system is to remove dust, salt and moisture before the compressor — not to wash them off later.
Air cleanliness and low ΔP must be balanced
Fine dust and aerosols foul compressor blades, restrict airflow and can accelerate erosion or corrosion. Excessive filter pressure loss also reduces the available inlet pressure. Stages are therefore selected for site climate, aerosol and dust loading, layout and the limits of the specific turbine — not by one efficiency class alone.
Selection goes by class and site environment, not by part number. Desert and coastal arrangements differ — there is no universal one. A final stage without a working pre-stage does not last.
Sites and climates
Core inlet-filtration types
Sequential stages without pulse cleaning: weather protection, droplet removal, prefiltration and a compact final element. Suits moderate dust loading and demanding moisture control.
- Plus: no pulse valves or piping
- Watch: the life of each stage
Cylindrical or conical cartridges are cleaned by reverse compressed-air pulses. Used under high dry-dust loading where long operation between changeouts is required.
- Plus: regeneration in operation
- Watch: compressed-air quality
A cleanable stage handles the bulk dust load while a static final element retains the most penetrating particles. Selection considers total ΔP, space and service strategy.
- Plus: combines life and a barrier
- Watch: total ΔP
For fog, rain, evaporative cooling and salt aerosol, the system uses weather louvres, coalescing media, drainage and hydrophobic stages. Water must be removed before the final stage.
- Plus: droplet protection
- Watch: drainage and water carry-over
From weather protection to the final barrier
Stops debris and combines fine droplets into drainable water. It does not replace the particulate stage.
- Hoods, louvres, snow screens
- Mesh and vane mist eliminators
- On the coast — a separate coalescing stage for salt aerosol
Capture coarse and medium particles to protect the costlier final stage. Pockets must remain stable at design airflow.
- Class: G4 – M6 (EN 779), ISO 16890 ePM10
- Changed 3 – 4 times more often than the next stage
- Without a pre-stage the final stage is changed several times more often
High mini-pleat area in a rigid frame. Efficiency class and terminal ΔP follow the turbine OEM requirement and project design.
- EN 1822 E10 – E12: 85 / 95 / 99.5% at MPPS
- Glass fibre and synthetic media, polyurethane seal around the perimeter
- Fitted only after a working F7 – F9 stage; a damaged seal cancels the class of the whole stage
- Every cassette comes with a test certificate
Self-cleaning stage for high dry-dust loading. A conical form supports dust release and pulse distribution in a dense array.
- Pulse-cleaned: F8 – F9 (EN 779), MERV 13 – 15; compressed-air pulse on ΔP
- Static: F7 – F9 (EN 779); no pulse, replaced on pressure drop
- Cellulose-synthetic, synthetic, ePTFE membrane; hydrophobic and oleophobic treatment
- Galvanised or stainless cage and end caps
Media selection follows dust, water, salt, temperature and cleaning duty. A hydrophobic finish does not replace correctly sized droplet separation.
- A membrane is needed where the dust is fine and sticky
- Hydrophobic treatment is mandatory with fog and high humidity
- This site limits a standard cartridge to a maximum of 135 °C; the actual operating limit comes from the complete-assembly datasheet
The design may include silencers, anti-icing, evaporative cooling or chilling. Their effects on moisture, ΔP and flow uniformity are assessed together.
- Housings and transition sections for the existing intake
- In winter — protection from snow and icing
Static, pulse-cleaned or hybrid system
- Static
- Low–medium
- Pulse-cleaned
- Medium–high, mainly dry
- Hybrid
- High with a final barrier
Stages, classes and scales
| Parameter | Value |
|---|---|
| Stages | 2 to 4, depending on site conditions |
| Classes | EN 779 F7 – F9 · EN 1822 E10 – E12 |
| ISO scale | ISO 16890 ePM10 / ePM2.5 / ePM1 |
| ASHRAE scale | MERV 11 – 16 to ASHRAE 52.2 |
| EPA classes | E10 — 85% at MPPS, E11 — 95%, E12 — 99.5%; MERV 16 ≈ E11 – E12 |
| Versions | pulse self-cleaning or static |
| Prefilter replacement | 3 – 4 times more often than the next stage |
| Standard cartridge temperature | 135 °C maximum (actual limit from the assembly datasheet) |
Filter class is only one part of the specification
- What it evaluates
- Efficiency and dust loading of turbomachinery intake filters
- How it is used
- Comparable element test data
The standard edition, conditioning method, airflow, aerosol and terminal ΔP criterion must be fixed in the technical specification. A class label without test evidence does not replace engineering review.
Input data for inlet-system design
For Uzbekistan and Kazakhstan, dust storms, mineral and cement dust, hot summers, seasonal cold, fog and rapid humidity changes are especially relevant. The configuration is based on measured site data, not the region alone.
- 01Turbine and airflow
Model and OEM limits, minimum/rated/peak airflow, allowable initial and terminal ΔP.
- 02Site
Temperature, humidity, rain, fog, wind, dust events, altitude and seasonality.
- 03Contamination
TSP/PM, particle distribution, mineralogy, salts, industrial aerosols, oil and nearby dust sources.
- 04Operation
Filter-house size, changeout access, compressed-air availability, target interval and permitted outage window.
We inspect the entire inlet path, not the filter alone
- ΔP by stage and its trend over time
- Frame, clamp, door and bypass-air sealing
- Pulse valves, receiver, nozzles and compressed-air quality
- Coalescer, drain pans, slopes and free drainage
- Correlation of compressor fouling, washing and power loss with filter condition
Frequently asked questions
Which filter is best for a dusty climate?
Pulse-cleaned or hybrid systems are often considered for high dry loading. With sticky dust, fog or a weak compressed-air supply, a static multistage system may be more reliable. Site data decide.
Can a higher-efficiency filter be installed?
Only after checking initial and terminal ΔP, airflow, frame size, sealing and OEM limits. A higher class without calculation may create unacceptable restriction.
Why does pulse cleaning fail to recover the cartridges?
Check receiver pressure and volume, pulse duration, valves and nozzles, leaks, compressed-air moisture, media condition and dust properties. Wet or sticky dust often will not release by pulsing.
Is a coalescer needed in a dry region?
Rain, morning fog, rapid humidity changes or evaporative cooling may still occur. The need is determined from weather data and the inlet design; moisture protection should not be dismissed on regional climate alone.
When should final V-cell filters be replaced?
By the agreed terminal ΔP, damage, wetting, particle breakthrough or service interval, subject to OEM limits. One stage is normally changed as a set to retain even airflow.
Can elements be upgraded without modifying the filter house?
Sometimes, using existing frames or an adapter. Dimensions, compression, bypass leakage, area, velocity, ΔP and service access must be checked first. If media area is insufficient, the housing needs modification.
Elements of the intake stages
Conical and cylindrical cartridges, V-bank cassettes and pocket prefilters — in the 3D catalogue.
We prepare the stage map and total ΔP calculation
For an operating unit we start with the turbine model, filter-house photos, element dimensions, ΔP history and site conditions. For a new project we agree classes, tests and replacement criteria in the technical specification.