1.7.2 System Components Description-9HA GT Inlet Air System

2.0 System Component Description

2.1 Filtration

Insect screen : made of steel/steel panels which have to be removed for winter season, avoid mosquitos to reach filtration stages ad to quickly clogged them.

Weather Hoods: Six hoods protect the filter housing intake. Each hood is made of a painted carbonn steel sub structure covered by cladding sheets. Lifting lugs and water draining gutter and pipes are fitted with each hood.

Coalescer Stage: Composed of an arrangement of support holding frames. AISI type 304L, fitted with water draining gutters and pipes. This frames support the 576 coalescer panels made of fiberglass fiber packaged in a plastic frame used for water droplet removal.

Pre Filter and High Efficiency Filter (HEF) Stage: Composed of a V shape support holding frame arrangement, made of AISI 304L. Each horizontal row of holding frames is inclined of 10 degree to evacuate water captured in the filter elements. Gutters and drain pipes enable water draining outside of the filter housing. Holding frame arrangement is designed to support 512 pocket type pre filters and 512 HEF cells. Pre filters are reverse installed against the front face of HEF cells and maintained by a stainless steel wires basket. Pre Filters efficiency class G4 (EN779) are made of synthetic fibers, a plastic header fitted with a gasket for sealing when installed against HEF. HEF efficiency class F9 are of made of fiber glass media, a plastic frame fitted with a gasket for sealing when installed in the support frame.

2.2 Closing Flap

Enable to close and to isolate the inlet air path from the cold ambient conditions during GT stop periods.

2.3 Anti Icing / Heater

Water/Air heat exchanger is used to prevent frost or ice forming on the filtration stages and other stiffeners, silencer baffles are located int he air path during icing events. Exchanger system is also used to heat ambient air, to follow the minimum air temperature(-29 degree Celsius) admissible at compressor intake (heater function).

2.4 Bleed Heating

Hot air extracted from the GT compressor when required by the bleed heating function (guarantee of NOx emission, protect IGV against icing) is dispatched in the filter housing by the bleed heating(IBH) manifold. The IBH manifold is composed stainless steel acoustical nozzlws through the filter housing air path.

2.5 Implosion Doors

Implosion door equipped with electro magnetsm limit swictches, heating gaskets open (2300 Pa) to prevent from inlet system implosion in case of high high pressure drop level reached during shutdown period.

2.6 Inlet Duct and Silencer

Inlet duct and silencer system is composed of one Elbow, one silencer section, one extraction joint and one support structure.
The elbow and the silencer duct structure are made of stiffened carbon steel sheets protected against corrosion by a painting system.
Noise reduction is achieved by an arrangement of parabllel baffles, Baffles are made of stainless steel type AISI 304L structure and perforated sheets which protect the acoustic cushions made of mineral wool and fiber glass fabric.
As additional acoustic treatment, inlet duct walls are externally insulated with mineral wool and cladding.

2.7 Inlet Plenum

Inlet plenum is composed of a casing structure in several parts; a cone, a support structure. Casing structure and cone are made of stiffened carbon steel protected against corrosion by a painting system.
The plenum is fitted with pressure, temperature and dew point measurement connections. A drain connection located in the plenum floor enables washing water evacuation.

1.7.1 Gas Turbine 9HA Air Inlet System

1.0   System Description

1.1    Main Function

The main function of the system are:

·         To remove water and dust particles from the atmosphere air sucked by the gas turbine compressor(air filter housing)

·         To covey filtered air towards the inlet plenum and to reduce gas turbine compressor noise(inlet duct and silencer).

·         To collect and distribute filtered air to the GT compressor intake.

 The inlet & exhaust system is an open loop where:

·         The air filter housing function is the removal of contaminants from the ambient air sucked by the FT compressor. Clean air is required by the combustion, the hot parts s cooling air system and to avoid corrosion, erosion and fouling of mechanical components such as compressor sand turbine blades.

·         Insects screen enables to catch big amount of insect which could clogged very quickly the pre filters stages, and so avoid frequent maintenance of pre filtration stages.

·         Inlet weather hoods and coalesce stage are used to remove water droplets. Dust Particles are removed by pre filter and high efficiency filtration cells.

·         A closing flab enables inlet system closing in case of long FT stop period to avoid very cold air circulation through compressor and Gas turbine.

·         Anti-icing protection of the inlet system components is ensured by a water/air heat exchanger. Exchanger also enables to guarantee the minimum ambient air temperature (-29 C) required at the compressor.

·         A bleeding heating manifold with acoustical nozzles dispatches air extracted from compressor in GT part load, to protect IGV stages from icing and to respect Nox level.

·         The mechanical security of the inlet system ducting and housing is insured by pressure drop monitoring which controls a GT Run Back in case of high pressure drop level reached and by implosion doors’ opening.

·         The air inlet duct system including the inlet silencer is used to convey atmospheric filtered air towards the inlet plenum. Inlet silencer enables to attenuate noise generated by the GT compressor.

·         The inlet plenum collects the atmospheric air and allow the inlet compressor feeding with a homogeneous distribution.

1.2    Components of Air intake System.

GE Code	Function
Weather Hoods	Protect filter housing against rain water from entering into the intake system.
Closing Flap	Close inlet system to avoid cold air circulation during GT stop period.
Water/Air Heat Exchanger	Operates as Anti icing system to protect filters against frost and as heater to guarantee min. required Temp. At compressor inlet.
AIBH manifold	Dispatch air extracted from GT compressor in the inlet system to cover the BH functions.
Pre filter and high efficiency stage	Remove dust particles from ambient air sucked by GT compressor.
Inlet silencer	Drive filtered ambient air towards the inlet plenum. Reduce noise coming from GT compressor.
Inlet plenum	Collect and distribute air to the GT compressor intake (IGV).

 

1.6.0 GT 9HA Bearings

General

The 9HA.01 gas turbine unit has two double tilting pad journal bearings which support the gas turbine rotor and two self-equalizing tilting pad thrust bearings to maintain the rotor-to-stator axial position. These bearings are incorporated in the inlet casing and exhaust frame which are supplied oil from the main lubricating oil system.

Lubrication

The main turbine bearings are pressure-lubricated with oil supplied, from the oil reservoir. Oil feed piping where practical, is run within the lube oil drain lines, or drain channels, as a protective measure. In the event of a supply line leak, oil will not be sprayed on nearby equipment, thus eliminating a potential safety hazard.

The oil flows through branch lines to an inlet in each bearing housing. When the oil enters the housing inlet, flows into an annulus around the bearing. From the annulus, the oil flows through machined holes or slots to the bearing rotor interface.

Lubricant Sealing

Oil on the surface of the turbine shaft is prevented from being spun along the shaft by oil seals in each of the bearing housings. These labyrinth seals are assembled at the extremities of the bearing assemblies where oil control is required. A smooth surface is machined on the shaft and the seals are assembled so that only a small clearance exists between the oil seals and the shaft. The oil seals are designed with tandem rows of teeth and an annular space between them. Pressurized sealing air is admitted into this space to prevent lubrication oil reservoir is vented to atmosphere after passing through an oil vapor extractor.

Load Coupling

A rigid, hollow coupling connects the forward compressor rotor shaft to the generator. A bolted flange connection forms the joint at each end of the coupling.