GENERAL   EQUIPMENT   INC.                    

Scope of Supply

    1.    Gas turbine generator package
 

    2.    Mechanical

·         Gas Turbine

·         Air Compressor

·         Combustors

·         Turning and Reduction Gear

·         Air Inlet facilities (Filters and Ducts)

·         Exhaust facilities (Ducts, Silencer) (less exhaust elbow )

·         Starting Motor system

·         Dual Fuel Combustors

·         Lube and Control Oil System

·         Closed Circuit Cooling Water system

·         Atomizing and Cleaning system

·         Instrument Air system

·         Enclosures, including HVAC, Fire-fighting, Electrical Switchboard for:

    - Gas turbine unit (external and internal)

    - Gas turbine auxiliaries

    - Electrical Switchgear

    - Control

    - Closed Circuit auxiliaries

    - Water Injection

·         GT Supervision, Control and Protection Systems

·         Fire Fighting (detection and protection) system

·         Gas Detection system

·         Thermal Insulation and Lagging

·         Compressor Washing and Cleaning facilities
 

        3.    Electrical
 

·         Electrical Generator, auxiliaries and related equipment (Circuit Breaker, Grounding Switch, Bus duct, Neutral Grounding cubicle, etc.)

·         Starting Motor system

·         Unit Transformer (11/6 kV) and auxiliary MV/LV Transformers

·         Main Switchboards (6 kV, 380 V PC, 380 MCC and emergency MCC) and MV isolated bus ducts

·         Auxiliary Switchboards (Generator Protection, HVAC, Fire-fighting, Lifting facilities, etc)

·         110 DC Power System

·         Uninterruptible Power System (UPS)

·         AC/DC Electrical Motors (DC Motor starters included)

·         Electrical Protection system

·         Lighting and Motive Power system, Heat tracing, Grounding, etc.

·         Cables and Cable Trays

        4.    Instrumentation & Controls

·         On board Instrumentation

·         Instrument Panels and Junction boxes

·         Control, Protection and Monitoring Panels

·         MMI (man-machine interface)

        5.    Miscellaneous

·         Special Tools

·         Anchor Bolts and Plates

·         Stair and Ladders

·         Steel Structures

        6.    Special Tools and Maintenance equipment (for the above mentioned machinery)

        7.    Operating and Maintenance Manuals
 

PERFORMANCES:     SIMPLE CYCLE

The following Gas Turbine performances:

ISO Conditions

With reference to the following conditions:

Ambient Pressure:                                            1013 mbar

Ambient Temperature:                                     15 °C

Relative Humidity:                                             60 %

Gas Turbine Inlet/Exhaust Pressure drop: 89/127 mm H₂O

The Plant Performances at Generator terminals when the plant is operated at GT new and clean conditions shall be:

Base Load

Output Power:             126 MW

Heat Rate:                     10096 BTU/KWh   (10650 kJ/kWh) (natural gas)

Gas Turbine and Auxiliaries

Gas Turbine

General description:

The PG9161(E) GT package was developed by a GE/ EUROPE authorized licensee with the frame 9E as basic equipment and within the license agreement with General Electric Co. (USA).

The PG9161(E) is a single shaft, high efficiency gas turbine for power generation in 50 Hz grids, suitable for simple cycle and combined cycle application.

The engine is designed for 3000 rpm nominal speed, to be directly coupled to a two-pole synchronous electric generator. This gas turbine unit includes all features and design solution coming from the operating experience of the MS9000 family, whose evolution has brought to the PG9161(E) one of its highest reliability value. The PG9161(E) unit consists of three compartments, one housing the auxiliaries, one the gas turbine itself, and the last one housing the exhaust plenum. Each compartment is equipped with access doors for easy site inspection and maintenance. The rotor is a single shaft assembly consisting of one compressor rotor joined to one turbine rotor by a flanged joint, and lays on three journal bearings (two elliptical and one tilting pad type). Two thrust bearings; one Kingsbury type (loaded) and one tilting pad type (unloaded) are also provided.

Compressor:

The compressor rotor consists of 17 stages with 12.3/1 overall compression ratio. The compressor rotor consists of 15 wheels, shrunk onto a forged shaft (rotor stages 2^nd to 16^th), two stub shafts (1^st and 17^th rotor stages), 16 tie bolts and stator/rotor blades. The stationary blades are assembled into two half rings (diaphragms) for each stage; the diaphragms are fitted into the compressor casing. The rotating blades are fitted on the discs by dove-tail roots and fixed by means of pins. The compressor external casing is totally made of grey cast iron. The compressor front portion contains the Inlet Guide Vanes (IGV) device that allows modulating the inlet flow during start up and optimize performance at part load operation. Air bleed ports provide cooling air for 1^st and 2^nd turbine stages (stationary and rotating buckets). The compressor end portion that discharges the air mass flow into the combustion chamber contains the compressor diffuser, devoted to eliminate flow swirl and then improve diffuser efficiency.

Combustion Section:

The PG9161(E) combustion system has been designed in order to ensure reliability, durability and flexibility, even in case of using different fuels. The combustion system is contained in a carbon steel casing which is part of the compressor-combustor shell and provides housing for combustor wrapper, combustions chamber assemblies, fuel nozzles, spark plug ignitors, UV flame detectors, cross flame tubes, transition piece. The combustion takes place in 14 combustion chambers, circumferentially arranged around the machine axis. The hot gas flows from the combustion chambers toward the turbine section via 14 "S" shaped transition pieces. This special arrangement ensures a good mix between the film cooling air and the combustion gases, thereby optimizing the gas temperature pattern at the first turbine stage inlet. The combustion section consists of Hastelloy cylinders joined together with corrugated rings, which lead the cooling air film along the wall, thus improving cooling.

The combustion chambers are installed and removed without lifting the combustor casing cover, in order to facilitate inspection and to reduce the inspection time. The transition pieces connecting the combustors to the turbine inlet are manufactured with NIMONIC 263 alloy, which yields good anti-corrosion properties together with high cracking resistance, and is furthermore easily weld able for maintenance at site, without needing heat treatment. Spark plug igniters, located in the 10^th and 11^th combustion chambers, are used t ignite the fuel/air mixture; the remaining chambers are ignited through cross flame tubes that provide connection between every two adjacent combustors. Two ultraviolet (UV) flame scanners, located in the 4^th and 5^th combustion chamber are provided to detect ignition during start up. The fuel is injected into the combustion chambers through fuel injectors, one per each combustion chamber, which are provided for single fuel operation.

Turbine:

The 3-stage turbine rotor is constituted by 3 discs, forged in alloy steel and coupled each other by bolted connections.

All rotating blades are precision cast, and are attached to the wheels by straight, axial-entry, multiple-tang dovetails that fit into matching cut-outs in the rims of the wheel. The turbine stationary blades (nozzles) are precision cast according to the following table:

The cooling flow for the cooled profiles is bled from suitable compressor stages (see compressor section). The space between 2^nd and 3^rd rotor wheels is also cooled by compressor bleed air. Nozzle diaphragms are attached to the inside of both 2^nd and 3^rd stage nozzle segments. These diaphragms prevent air leakage past the inner sidewall of the nozzles and the turbine rotor. A turbine shroud is included, whose main function is to provide a cylindrical surface for minimizing bucket tip clearance leakage (a secondary function is to provide a high thermal resistance between the hot gases and the comparatively cool shell). This reduces the shell-cooling load and allows controlling the shell diameter and roundness and turbine clearances. The shroud segments are maintained in the circumferential position by radial pins from the shell. Joints between shroud segments are sealed by interconnecting tongues and grooves.

Exhaust Frame and Exhaust Plenum:

The flanged end of gas turbine shell is bolted to exhaust frame. On the structural point of view, the frame consists both of an outer and an inner cylinder, interconnected by radial struts. The GT end journal bearing is supported from the inner cylinder. The exhaust frame, fabricated in ASTM A435 carbon steel, receives gas flow from the GT diffuser, and is connected to the exhaust plenum by flexplate expansion joint.

The exhaust plenum consists of a box, open at one side and welded to its own base. It is fabricated in carbon steel, lined with 409 SS chromium steel sheet. Thermocouples for measurement of exhaust gas temperature and for transmitting the values to the GT control system are located in the final part of the exhaust plenum.

Gas Turbine Control System (SUMIVAC)

Gas Turbine Auxiliaries:

The Gas Turbine includes the following auxiliaries:

• Oil Systems (Lubricating Oil system, Control Oil system)

• Inlet Air system (Filtration system, Inlet Air duct, etc.)

• Exhaust Gas facilities (silencer, vertical stack)

• Fuel system (dual fuel: natural gas, diesel oil)

• Compressor Washing system

• Enclosures including HVAC, Fire-fighting, etc.

• Lube Oil closed circuit Cooling Water system

• Instrument Air system

• Fire Fighting system (CO2 and dry chemical type)

• Gas Detection system

• Electrical equipment (Generator Neutral Grounding Cubicles, Generator Protection)

• Board, Low Voltage Distribution Board, Power Control Centre, Motor Control Centers, DC Power system, Uninterruptable power supply, Cables, Induction Motors, Grounding system, Vibration monitoring and protection system, Indoor Lighting system).

Electrical Generator:

The electrical Generator is a synchronous machine, ventilated in open air-circuit, with air-exchanger shell & tube cooler provided. Characteristics of generator as follows: 

NOTE:  Closed Cooling Cooler not included. Special Design for climate conditions

Rated Output:                                          163 MVA**

Rated Terminal Voltage (± 5%):          11.000 V

Rated Phase Current:                            7400 A

Rated Power Factor:                              0.85

Frequency:                                               50 Hz

Speed in RPM:                                         3000

Design Temperature:                             As per IEC 34

Insulation:                                                 Class F

Maximum Air Inlet Temperature:         40°C

Generator Excitation System:              Static type

Response Ration:                                    >1.9 s^-1

Power Consumption at rated load:     ≈290 kW

** The Generator is oversized to allow upgrade to PG-1971-E at first overhaul.

Electrical Systems:

GAS TURBINE Generator:

The GT generator, endowed with related auxiliary systems and devices, shall be rated to operate continuously at full load.

The excitation system shall be static type with automatic and manual Automatic Voltage Regulator (AVR) system.

The main functional generator characteristics shall be as listed below:

      at 835 m.

Step-up Transformer (NOT INCLUDED)

Unit Transformers (included)

Unit Transformers:

The Unit transformer shall be sized to continuously supply its own GT auxiliary services and BOP loads.

The transformers shall be mineral oil immersed, forced cooled, outdoor type. An off-load tap changer on the HV winding shall be provided.

The main functional characteristics of transformers are listed below:

Isolated phases Bus Ducts and Generator Breakers

The connection between generator and its associate step-up transformer shall be made using isolated phase bus bars - IPB (each phase conductor being enclosed in an individual metal housing separated from adjacent conductor housing by an air space).

Regarding the gas turbine, a tapping on the generator transformer connection shall enable the supply of the step-down transformers. This tapping connection shall be made using isolated phase bus bars (IPB).

Each gas turbine generator breakers shall be installed in the run of its own bus ducts and shall be sized for the maximum calculated current.

A disconnect switch with grounding switch on the side of the step-up transformer shall be provided.

 
MV Switchboards:

The MV switchboards shall supply the auxiliaries above 200 kW.

The 6.6 kV switchboards shall be metal clad, of the prefabricated type, for with-draw out units and magnetic blast or SF₆ breakers. They shall be made of independent, standardized and sectional units. In each unit, the cubicles for the circuit breakers, the bus-bars for the cable terminals, the voltage transformers and the low voltage equipment shall be completely segregated.

The GT switchboard UAB shall be fed by the relevant unit step-down transformer UAT and shall feed the gas turbine starting motor, the gas turbine static excitation system, the LV auxiliaries via 6.6/0.4 kV transformer.

LV Switchboards:

Power Centers:

The Power Centers shall be metal clad, of the prefabricated type, for draw out units and magnetic-blast breakers. They shall be made of independent, standardized and sectional cubicles. In each unit, the cubicles for the circuit breakers, the bus bar area for the auxiliary equipment and the cable terminal areas shall be completely segregated.

The unit power centre is divided into two sections, which can be connected through a bus tiebreaker. The first section UAB-1of the switchboard is directly fed by the unit auxiliary transformer. It supplies power to the gas turbine motor control centers (UAC-1, UAC-2, UEC) and to the lighting switchboard ULN-B. The second section is supplied by a station 33/0.4 kV transformer. It supplies the diesel oil pump station motor control centre and gives a back-up supply to the gas turbine emergency motor control centre (UEC) and to the GT emergency lighting switchboard (ULE-B).

Motor Control Centers:

The Motor Control Centers shall be of the prefabricated type, with draw up components for an easier maintenance. In the switchboards, manually operated circuit breakers shall be installed.

The GT switchboards UAC-1, UAC-2, UEC shall be fed by the respective LV switchboards UAB-1 and shall feed the respective 380 VAC loads for GT.

The switchboard OPC shall be fed by the LV switchboard UAB-2 and shall feed the diesel oil pump station and the plant fire fighting auxiliaries.

Generator Protection System:

The generator protection system shall be made in two separated and redundant sections (Channel A and Channel B), and shall be supplied by two independent line feeders.

General Features

• The automatic synchronizing device shall be three-phases type, to avoid connection of the generating equipment to the HV grid unless all phases of HV supply are energized;
• Maximum voltage, minimum voltage and minimum frequency electric protections shall be provided to disconnect the generator from the system when a system abnormality occurs that could result in an unacceptable deviation from nominal voltage or frequency at the point of supply;
• An unbalance current operation protection shall be provided to disconnect the generator from the HV system, in the event of loss of one or more phases of HV supply to the installation
• In the event of failure of any supplies to the protective equipment, audible and visual alarm shall be provided. Alarm operation shall be followed by timered automatic disconnection of the plant.

In the following table the generator protection to be provided are listed:

(1) Over frequency protection realized on the gas turbine protection system.

Generator Neutral Grounding System:

The generator neutral shall be then earthed via a single-phase, 50 Hz, dry-type transformer. The secondary transformer winding shall be shunted by suitable grounding resistor. The transformer shall be sized to give an equivalent resistance to the capacitive reactance of the unit connected system, and rated for short time overload; the secondary resistor shall be a cast-grid type rated for short time (20 s) loading.

All generator neutral grounding components shall be installed into a suitable enclosure for outdoor service.

The generator neutral grounding system shall consist of the following major components:

• Neutral grounding transformer
• Secondary resistor
• Neutral grounding disconnecting switch
• Neutral grounding bus
• Terminal blocks;
• Enclosure for outdoor service.

Electrical Motors:

The motors shall comply with IEC relevant standards. They shall be able to start their loads even with a transient 20% voltage depression.

6.6 KV AC Motors:

The motors rated more than 200 kW, shall be fed from the MV power supply.

The motors shall be of the asynchronous type with cage rotor, rated for direct start-up at full load and continuous service, of the closed air circuit type. The stator winding shall have insulation class F, with a class B temperature rise during operation.

3.3.9.2 380 V AC Motors

The motors rated less than 200 kW, shall be fed from the 380 V ac systems.

The motors shall be of the asynchronous type with cage rotor, rated for direct start-up at full load & continuous service. The motors shall be air-cooled type. The insulation class shall be B.

Direct Current Supply System

A 110 V Direct Current Supply System shall feed Gas turbine auxiliary loads. The system shall feed process solenoid valves, MV and LV equipment coils, and the emergency auxiliaries used to shutdown when the 380 V ac power sources are totally lost (emergency lube oil pump, jacking pump, etc.).

The system shall consist of:

• Lead Storage Battery. The battery sizing shall be suitable to supply for 1 hour all the DC loads necessary to ensure a safe emergency shutdown of the relevant turbine and the site auxiliaries. The battery shall supply DC current when there is a failure of the rectifier or there is a lack of AC voltage on the rectifier input.
• Rectifier, sized to feed all the DC loads and, at the same time, to re-charge the storage battery.
• 110 V Distribution Switchboards ACC, BCC or 1CC that shall feed all the relevant DC loads.

Uninterruptible Power Supply (UPS) System:

The system shall feed the digital control and instrumentation system, operator interfaces equipment, process specific equipment which requires an uninterruptible supply and centralized control equipment (turbine set control equipment, etc.).

Each UPS system shall consist of:

• Inverter, fed by the 380 V ac emergency motor control center. The inverter shall supply a 220 V/50 Hz stabilized power supply
• 220 V AC Distribution Switchboards

Lighting and Motive Power Supply System

General Description:

The lighting system shall be a four-wire distribution feeding both single phase and three phase loads, consisting of:

• Main Distribution Switchboards
• 380/400-230 V/V Transformers, fed by Power Centers
• Sub-distribution Switchboards.

The Lighting Switchboard shall consist of 3 sections, as indicated below:

• Plug connection section (sized for 12 kA symmetrical short circuit current)

• Normal lighting section (sized for 7 kA symmetrical short circuit current)

• Emergency lighting section (sized for 7 kA symmetrical short circuit current)

During normal operation, the emergency lighting section shall be fed by the plug connection section but, when the normal power supply fails, it could be fed by the 33 kV system through the UAB-2 switchboard and a 380/400-230 V/V transformer. An automatic transfer device shall be enabled by the low voltage bus bar relay, and shall switch from the normal to the emergency power supply.

Safety, Emergency and Normal Lighting Systems

Three different lighting systems shall be provided:

• Safety Lighting System

It shall be dedicated to light all the rooms where personnel shall operate under emergency condition and all the escape ways. Lighting for emergency operation shall be fed by the DC system. The local lamps, endowed with their own self-supplying batteries, shall be provided to lighting the escape ways.

• Emergency Lighting System

It shall be dedicated to integrate the lighting for areas where safety lighting is to be provided and to provide a partial lighting for external areas of the Plant. Moreover, the emergency lighting system shall feed the self-supplying system of safety luminaries.

• Normal Lighting System

The lighting system shall ensure a sufficient illumination level to all the Plant areas. The outdoor lighting system shall be realized by means of high mast lighting poles with high-pressure sodium or metal halide lamps, integrated with lighting poles with fluorescent lamps.

The three lighting systems shall contribute to achieve the following illumination levels:

Plug Connection Supply System:

The plug connection system shall feed the building heating system, the lifting equipment, the workshop tools, etc.

In order to supply the portable tools, socket outlet shall be available in each room and plant area. The sockets shall be arranged so that the length of the portable tool cords shall not exceed 15 m. The sockets shall be standardized in accordance with the following types:

• three-phase + ground socket of 63 A, with mechanically interlocked switch
• two-phase + ground socket of 16 A, with mechanically interlocked switch
• two-phase + ground socket of 16 A, for loads under than 1 kW.

Communication System

Grounding System:

All metal and civil structures, electrical machines and equipment shall be linked to an gounding system consisting of a grid earth electrode, grounding conductors and bonding conductors.

The grid earth electrode shall be built using copper stranded conductors of 90 mm² cross section buried at a depth of 0.8 m. It shall be linked to foundation earth electrodes and to natural earth electrodes (metallic structures in conductive contact with the earth).

Grounding system shall be sized in compliance with the European Standard.

Grounding system characteristics shall be as follows:

• earth grid consisting of copper stranded cable with sectional area of 90 mm²
• depth of earth grid conductor: 0.8÷1 m
• Grounding conductors consisting of copper stranded cables;
• bonding conductors consisting of:

- copper stranded cable

- copper strip

- hot galvanized steel strip

- insulated cables with section not lower than phase section.

To avoid interferences during the earth faults, different earth connection to the buried grid shall be realized for instrumentation.

Electrical Control System

The operation and control of the MV and PC's LV switchgears shall be normally controlled from the gas turbine Control Room.

A synchronization device shall be installed in the control panel for the automatic synchronization. The synchronization shall be operated by the generator breaker.

Cables and Cable Trays

Cables

All MV and LV cables shall be rated for the maximum voltage value of the system, worst environment thermal conditions and maximum current value.

Minimum cables section shall be calculated according to the following criteria:

• MV cables: short circuit current, calculated on main bus bar;
• LV cables (Power Center): short circuit current, calculated on main bus bar;
• LV cables (Motor Control Center): short circuit current, calculated on loads.
   

Multipolar MV cables shall be armored.

Raceways (recommended)

For raceways tunnels, cable trays and conduits shall be used. Cable trays and conduits shall be made of steel, hot galvanized type.

Different cables ways shall be provided for instrumentation to avoid interference caused by fault current of power circuit.

Raceway shall be separated for the following cables:

• MV cables
• LV cables
• controls cables
• Instrumentation cables

Cables employed for feeding of redundant loads and systems shall be on separated raceways.

Automation System

Gas Turbine

The GT unit will be equipped with Control System and will be operated from the Operator Station located in the Local Control Cabinet.

DUAL Fuel Oil System

The local gas turbine will be monitored by control system.