AIS 2005 NTPC

Air Intake SystemAir Intake System

S Dev RoyS Dev Roy

National W/S AIS 2005National W/S AIS 2005

Slide no Slide no 22 :: :: 2 May 20232 May 2023 :: :: 05:15 AM05:15 AM

IntroductionIntroduction

A gas turbine consumes A gas turbine consumes an enormous amount of an enormous amount of air.air.

Gas Turbines are Gas Turbines are sensitive to the air quality.sensitive to the air quality.

Necessity of inlet air Necessity of inlet air filtration for full filtration for full performance, reliability performance, reliability and maintainability of gas and maintainability of gas turbines.turbines.



Why filtration is requiredWhy filtration is required Abrasive solids Abrasive solids

Compressor fouling Compressor fouling

Wet corrosion by salt Wet corrosion by salt

Plugging of cooling passages Plugging of cooling passages

attack rotating parts.attack rotating parts.

alteration in profile and efficiency loss.alteration in profile and efficiency loss.

damage in the compression stage.damage in the compression stage.

fatigue from overheating. fatigue from overheating.



ImplicationImplication

A loss in mass flow A loss in mass flow

Continuous full load situations Continuous full load situations

Repair and maintenance Repair and maintenance

Replacement partsReplacement parts

Turbine efficiency to sufferTurbine efficiency to suffer

Increase in heat rate.Increase in heat rate.

Loose essential power output.Loose essential power output.

Increased water wash frequency Increased water wash frequency

Turbine blades are of tremendous cost.Turbine blades are of tremendous cost.



Relative sizes of common dust and particles Relative sizes of common dust and particles

Source: Donaldson Company Inc.



Effect of Particles Effect of Particles

Particle Size Particle Size (Microns)(Microns) ProblemProblem AffectAffect

10 µm and 10 µm and greater greater

Erosion of Erosion of turbine turbine blades blades

Permanent Permanent damage to damage to blades blades

5 µm and 5 µm and smaller smaller

Causes Causes deposits on deposits on bladesblades

Fouling affects Fouling affects air handling air handling characteristics. characteristics. Reduces output Reduces output efficiency.efficiency.

Compressor Blade CorrosionTurbine Blade Hot CorrosionPlugged cooling passages

Compressor Blade Erosion



Effects of Dust/ ParticlesEffects of Dust/ Particles Erosion Erosion

Corrosion Corrosion

Fouling Fouling

Plugged cooling passages Plugged cooling passages

Caused by large particles (usually 10 microns Caused by large particles (usually 10 microns and larger) hitting and damaging the turbine and larger) hitting and damaging the turbine blades. blades.

Caused by particles, chemicals, or vapors in the Caused by particles, chemicals, or vapors in the air, react with blade's metal properties.air, react with blade's metal properties.

Build-up of particles on the downstream side of Build-up of particles on the downstream side of the compressor blades.the compressor blades.

Leakage of contaminants cause a buildup in the Leakage of contaminants cause a buildup in the cooling passages of the turbine blades.cooling passages of the turbine blades.



Effect of contaminants and countermeasuresEffect of contaminants and countermeasures

Constituent or Constituent or ParameterParameter Effect(s)Effect(s) Countermeasures / RemarksCountermeasures / Remarks

VanadiumVanadium Hot corrosionHot corrosion• Adjustment of the operating hours Adjustment of the operating hours

meter if limit is slightly exceeded. meter if limit is slightly exceeded.

LeadLead Hot corrosionHot corrosion • Strict adherence to limits Strict adherence to limits

Alkali metals (Na, K)Alkali metals (Na, K)Hot corrosionHot corrosion[Alkali sulphate [Alkali sulphate corrosion]corrosion]

• Fuel washing Fuel washing • Filtering of intake air (prevent Filtering of intake air (prevent

dissolution of salts retained in filter dissolution of salts retained in filter during rainy weather!) during rainy weather!)

• Demineralization of water Demineralization of water

WaterWater Clogging of filters, Clogging of filters, erosionerosion

• Fuel cleaning (centrifuging or electro-Fuel cleaning (centrifuging or electro-static separation) static separation)

Dust, sedimentsDust, sediments

Clogging of filters, Clogging of filters, erosion, formation of erosion, formation of deposits, hot corrosion, deposits, hot corrosion, acid corrosionacid corrosion

• Cleaning of fuel and intake air Cleaning of fuel and intake air (filtering, electrostatic separation) (filtering, electrostatic separation)



Type of filters and filter media can be as varied as Type of filters and filter media can be as varied as site locations for a power plant. site locations for a power plant.

We can categorize site locations in seven regions We can categorize site locations in seven regions geographically and environmentally. geographically and environmentally.

In many instances, it is possible to encounter In many instances, it is possible to encounter several environmental situations in one location, several environmental situations in one location, thus making proper selection of the intake filters thus making proper selection of the intake filters even more critical.even more critical.

EnvironmentEnvironment

RuralRural UrbanUrban CoastalCoastal Off-ShoreOff-Shore DesertDesert TropicalTropical ArcticArctic

Source: Pneumafil, Donaldson, AAF, Mueller, Braden, Camfil, Kaefer, G+H

We can categorize site locations in seven regions geographically and environmentally.



Weather: Sun. Rain. Mist. Generally dry. Temperature: 0° to 50° CTypes of Dust: Ploughing, harvesting, fertilizing, scrub burning and

other particulate dust producing activities.Wind blown erosive dust during the ploughing season.Wind blown fertilizer dust.

Dust Concentration: 0.02 - 10 mg/m3 *Particle size (µm): 0.01 - 30 *Potential damage: Erosion/Corrosion

Environment: Environment: RuralRuralLimited number of buildings. Light traffic. Limited number of buildings. Light traffic. Predominantly agricultural. Predominantly agricultural.

Indian ContextIndian Context

Recommended Inlet Air Filtration System Inlet Weather Hood Inlet Bird Screen

Pre & Fine Filter (Humid)Self-cleaning Filter (Dry) Inlet Air Cooling (if climatic conditions warrant)

* Source: Pneumafil



Environment: Environment: UrbanUrban

Weather: Sun. Rain. Fog. Temperature: 0° to 50° CTypes of Dust: Mainly dry, granular. Soot particles and fibers.

Particulate may contain corrosive elements. Some manufacturing complexes will generate their own types of particulate.

Dust Concentration: 0.05 - 0.50 mg/m3 *Particle size (µm): 0.01 - 10 *Potential damage: Fouling/Corrosion

Light industrial with residential areas. 90% developed. Light industrial with residential areas. 90% developed. Housing. Paved roads. Moderate traffic. Moderate air pollution.Housing. Paved roads. Moderate traffic. Moderate air pollution.


Recommended Inlet Air Filtration System Inlet Weather Hood

Inlet Weather Hood

Inlet Bird Screen Inlet Bird

Screen Self-cleaning Filter

Pre & Fine Filter

I Options II I Options II

* Source: Pneumafil



Environment: Environment: CoastalCoastal

Weather: Dry. Sunny. Rain squalls. Sea mists. Fog. Wet and dry salt. Winds on/off shore.

Temperature: 0° to 35° CTypes of Dust: Mainly dry, granular. Some soot particles. Fibers.

Wet and dry sea salt. Sulfate. Magnesium. Dust Concentration: 0.01 to 0.1 mg/m3 **Particle size (µm): 0.01 to 7.0 **Potential damage: Wet corrosion. Fouling.

Gas path corrosion.

RResidential areas. Some esidential areas. Some Light industryLight industry. . Housing. Paved roads. Light to Moderate traffic. Housing. Paved roads. Light to Moderate traffic.


Recommended Inlet Air Filtration System Inlet Weather Hood

Inlet Bird Screen Coalescer Demister

Pre & Fine Filter

Additional for Coastal/OffshoreMarine Vane Water Eliminator (Pneumafil)

D-Salt™ - Salt Removal System (Donaldson)HydroCel 95 Gas Turbine Filter (AAF)

* Source: Pneumafil



Environment: Environment: OffshoreOffshore

Weather: Dry. Sunny. Squalls. Rain. Fog. Gale force winds. Airborne spray and sea salt.

Temperature: 0° to 30° CTypes of Dust: Drilling cement dust. Barites. Drilling dust.

Flare carbon. Mud burning smoke. Grit blasts from platform maintenance activities.

Dust Concentration: 0.1 to 10 mg/m3 **Particle size (µm): 0.3 to 100 **Potential damage: Erosion. Wet corrosion.

Hot gas path corrosion.

Oil Rigs. Offshore platforms.Oil Rigs. Offshore platforms.


Recommended Inlet Air Filtration System Inlet Weather HoodSelf-cleaning Inertial Separator Pre & Fine Filter

Additional for Coastal/OffshoreMarine Vane Water Eliminator (Pneumafil)

D-Salt™ - Salt Removal System (Donaldson)HydroCel 95 Gas Turbine Filter (AAF)

* Source: Pneumafil



Weather: Little or no rain. Extended dry periods. High winds. Little or no rain. Extended dry periods. High winds. Sand and Dust storms. Sand and Dust storms.

Temperature: 0° to 50° CTypes of Dust: A sample analysis a site > 10 miles inland from a site > 10 miles inland from

nearest point on shorelinenearest point on shorelineConstituentConstituent Quantity (%)Quantity (%) ConstituentConstituent

Quantity (%)Quantity (%) Silica 50

Calcium 32 Magnesium 9

Alumina 5 Potassium 3

Sodium 1

Dust Concentration: 0.1 - 700 mg/m3 **Particle size (µm): 0.3 to 100 **Potential damage: Fouling. Severe erosion. Corrosion

Environment: Environment: DesertDesertEExtreme daily and seasonal fluctuations in wind speed. Varied xtreme daily and seasonal fluctuations in wind speed. Varied airborne particulate size, distribution and concentration.airborne particulate size, distribution and concentration.


Recommended Inlet Air Filtration System Inlet Weather Hood Inertial

Separator (Optional) Self-cleaning Pulse Filter or Augmented Self

Cleaning (ASC) Pulse* Source: Pneumafil



Weather: Hot and sunny. High humidity. Monsoon rains. Hot and sunny. High humidity. Monsoon rains. Insect swarms. Mist. Fog. Insect swarms. Mist. Fog.

Temperature: 5° to 50° CTypes of Dust: Ploughing, harvesting, fertilizing, scrub burning and

other particulate dust producing activities.Wind blown erosive dust in ploughing season.Wind blown fertilizer dust.Wet airborne sea salt at coastal areas.Wet airborne sea salt at coastal areas.

Dust Concentration: 0.02 - 10 mg/m3 **Particle size (µm): 0.01 – 30 *Potential damage: Erosion. Fouling. Corrosion

Environment: Environment: TropicalTropicalInland and coastal areas. Light / heavy Industry. Inland and coastal areas. Light / heavy Industry. Oil and gas activities. Urban. Dense vegetation. Oil and gas activities. Urban. Dense vegetation.


Recommended Inlet Air Filtration System Inlet Weather Hood Inertial

Separator (Optional) Inlet Bird Screen or Insect Screen

Moisture Elimination (Optional)Pre & Fine Filter

* Source: Pneumafil



Weather: Blowing snow. High winds. Hoar frost. Ice fog. Blowing snow. High winds. Hoar frost. Ice fog. Summertime insect swarms in some areas. Summertime insect swarms in some areas.

Temperature: -50° to 20° C Types of Dust: Silica. Quartz. Carbon. Iron. Iron oxide. Sodium. Dust Concentration: 0.01 - 0.25 mg/m3 **Particle size (µm): 1 - 15 **Potential damage: Wet corrosion. Foreign object damage due to ice

ingestion. Excessively high inlet restrictions due to snow / ice plugging of air intake paths.

Environment: Environment: ArcticArcticArctic and extreme cold weather. Oil production activities including Arctic and extreme cold weather. Oil production activities including electric power generation, gas compression, crude oil pumping. electric power generation, gas compression, crude oil pumping.

Recommended Inlet Air Filtration System Inlet Weather Hood Insect Screen Self Cleaning Pulse Filter

Required Modification Solenoid box heaters Control box heatersTrace heatingStainless steel air lines

* Source: Pneumafil



Experience: Experience: FaridabadFaridabad

In winter of 1999, a heavy fog prevailed on site. Delta p climbed to the trip value in early morning resulting

trip. Reason analyzed, a layer of a black / viscous material found

on filter media. Contributing elements were identified such as gyps, clays

and nitrates.

Self cleaning pulse filter system was selected based on tender documents.

Metrological data, over a period of 1951-601951-60 were taken from nearest observatory in New Delhi.

Immediate solution was given to wash the elements.

Proceed with the element change-out immediately before the fog season.

Capture finer fog by installing an extra coalescer in the hood/ synthetic Spider-web media.

An active coating on the media surface.

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Experience: Experience: Baiji, IraqBaiji, Iraq

These filters are working satisfactorily. No adverse report has been obtained from the site.

To suit dusty atmosphere at site, customer has chosen ASC filters only i.e. combined inertial separation and pulse cleaning.

On approach customer provided us the data regarding rainfall, maximum / minimum temperature, relative humidity and occurrence of dust storm in number of days.

Static filters which sustain the high pressure drop was provided.

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Experience: Experience: Western Mountain, LibyaWestern Mountain, Libya

The site is under construction.

To suit dusty atmosphere at site, customer has chosen ASC filters only i.e. combined inertial separation and pulse cleaning.

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Our RecommendationOur Recommendation

Tender specification should give following actual daily data for complete one year: Highest & lowest temperatureHighest & lowest temperature Highest & lowest humidityHighest & lowest humidity RainfallRainfall Highest & lowest oil vapour present in air Highest & lowest oil vapour present in air Highest & lowest hydrocarbon present in airHighest & lowest hydrocarbon present in air Highest & lowest dust concentration in air Highest & lowest dust concentration in air Highest & lowest salt concentration in air Highest & lowest salt concentration in air Period of fog & smog formation and concentration during the yearPeriod of fog & smog formation and concentration during the year

Change in environment is dynamic because of rapid urbanization. Old meteorological data provided in tender specification leads to

wrong selection of filter house.



Our RecommendationOur Recommendation Continuous monitoring of

environmental data. During subsequent erection at

the power plant hydrocarbons, vehicular traffic, gyps, air borne dust can choke the filter of earlier commissioned plant.

Interchangeability of different types of filters in the filter house if environmental data calls for.

Readiness to stock of different filter elements to replace them before ensuing of particular weather.

Help us to Help us to choose the choose the right media to right media to protect your protect your turbineturbine



Thank YouThank You

Documents

AIS 2005 NTPC