+ All Categories
Home > Documents > Gas Turbine Generator Presentation

Gas Turbine Generator Presentation

Date post: 14-Oct-2015
Category:
Upload: sagar-naduvinamani
View: 175 times
Download: 12 times
Share this document with a friend
Popular Tags:

of 25

Transcript
  • PRESENTATION ON

    GAS TURBINE GENERATORTurbine Package Main Parts Turbine General Arrangement and Systems TOYOs scope & ResponsibilitiesTurbine PerformanceBY :- A. S. BOROTIKAR 03 Nov.06Introduction About Gas Turbine

  • A -- IntroductionWorking principle of GAS turbine is Breton Cycle The simple cycle working cycle is two addiabatic cycles with one isentropic cycle the As an introduction , Gas turbine is a rotary engine which produces mechanical work. The continuous power cycle and rotor motion of the gas turbine provides several advantages over other types of heat engines, including relatively vibration less operation, fewer moving parts and wear points, reliability and a higher quality of ac power in generator applications. This Mechanical power generated by Gas turbines is widely applied for propulsion in aeronautics and marine field.

    On land, the application includes simple and combined power plants, supply of energy for chemical heating process, supply of energy for fluid compression, & for locomotive propulsion

    Theory of operation :- Gas turbines are described thermodynamically by the Brayton cycle, in which air is compressed isentropically, combustion occurs at constant pressure, and expansion over the turbine occurs isentropically back to the starting pressure

  • A Typical Gas simple cycle Gas Turbine Package Consist of Following Main Equipments, Accessories And Systems Gas Turbine Engine

    Driven Equipment ( Generator or Compressor)

    Starting System Lube Oil System Lube oil tank Lube oil pumps, (main, auxiliary ac, and emergency dc)Lube oil cooler Lube oil filters Oil mist eliminators Fuel Gas System Gas fuel scrubbers (filters)Control valves Primary and secondary shutoff valvesLiquid fuel boost up pump

    GT Enclosure with Fire Extinguishing System

    Water Wash System.

    Other Accessories for Maintenance

    B -- Turbine Package Main Parts, Arrangement And Systems

  • 1 -- GAS TURBINE ENGINEA simple open cycle non regenerative single shaft industrial gas turbine mainly consist of three zone :- Air Compression Zone :- Compressor draws in air from the environment and by adding mechanical energy , bring the system to the overpressure required to operate the cycle the modern gas turbines are always equipped with multistage axial compressors Combustion air inlet system consists of Inlet filters followed by silencer and the duct.The inlet guide vanes and the first three rows of stators are of the variable geometry type: they operate in two positions depending upon turbine speed. At start, the vanes are in the closed position, restricting the flow of incoming air. At the same time, the bleed valve, mounted. on the combustor housing, bypasses a portion of the airflow to the turbine exhaust. This modified airflow provides for smooth acceleration, a relatively low turbine inlet temperature, and ample compressor surge margin during acceleration. The bleed valve closes at 80% speed, followed by the vanes which begin opening at 90% speed and reach the full open position prior to full speed, allowing full airflow with rough the turbine.

  • 1 -- GAS TURBINE ENGINECombustion Zone :- The air leaving the compressor is raised to the required turbine inlet temperature by burning of fuel in the multiple combustors located annular gas turbines are always equipped with multistage axial compressors For stoichiometric combustion, the gas turbine requires approximately one-fourth of the total air it compresses. The excess air is used to cool the combustion chamber and mixes with the combustion products to reduce the gas temperature at the inlet to the first turbine stage. The cooling air keeps metal temperatures in the combustion chamber and turbine section at design levels for long life . This system reduces pollution by limiting the formation of nitrogen oxides (NOx) and carbon monoxide (CO).

  • 1 -- GAS TURBINE ENGINEPower Generating Turbine Zone :- A series of rotating and stationary blades expands the hot gases producing mechanical power at shaft end. The hot gases leaves the turbine through exhaust diffuser.Combustion chamber and turbine blades are generally cooled by circulating bleed air form compressor. The gas turbine output shaft is mechanically attached to both the compressor and turbine sections of the engine to form a solid or single shaft configuration. This feature enhances speed stability and response under constant and varying load conditions a highly desirable feature in generator applications requiring precise frequency control.

  • TITAN- 130 SINGLE SHAFT GAS TURBINE

  • 2a -- Driven Equipment- Generator The mechanical power produced by gas turbine may be used to drive different equipment like compressors for compressing gas or liquids OR electric generators for producing electricity In industrial power generation package , generator is coupled with output shaft of gear box. There are may different arrangements for generator installation. It may either be installed on same skid in same Turbine enclosure or it may be outside separately. Generator system includes dedicated cooling fans which keeps the stator and rotor winding temp. within limit.

    Generator Frame: Provides the structural strength and rigidity for the generator and serves as a housing to guide cooling air flow

    Inner End Shield: Is a baffle used to form a path for cooled air

    Generator Fan: Provides continuous circulation of cooling air

    Rotating Field: A magnetic field which induces AC voltage in the stator windings

    Collector Rings: Provide a connection and path for DC power into the rotating field windings

    Main Coupling: Is the connection to the drive shaft

    Generator Coolers: Remove heat from the generator cooling air

    Stator Core: Houses the stationary windings and forms a magnetic path necessary for induced voltages

    Air Gap: Is the radial clearance between the rotating field and the stator core

    Stator Coil End Turns: Formed when coils leave one slot in a stator core and are returned to a different slot

    Terminal Leads: Serve to conduct the three phase voltage and current flow from the generator stator to the external system StatorRotorPermanent MagnetExciterCoolerOuter Casing

  • 2b -- Generator Working Fundamental and OperationWhen the rotor operates at synchronous speed, the permanent magnet generator provides power to the voltage regulator. The voltage regulator provides the appropriate exciter field current to control the exciter armature output which is rectified to provide dc power to the main generator rotating field winding Voltage transformers provide signals proportional to line voltage to the AVR where it is compared to a stable reference voltage. The difference (error) signal is used to control the output of the exciter field. For example, if load on the generator increases, the reduction in output voltage produces an error signal which increases the exciter field current resulting in a corresponding increase in rotor current and thus generator output voltage.

    GENERATOR OPERATION

    When a generator is used to supply power, it can be operated in the following modes: isolated (sometimes referred to as island) mode or parallel with a system or other machines. In both cases, the power (WATTs) supplied at the generator terminals is a function of the fuel supplied to the prime mover, which is controlled by the governor.

    .

    ISLAND OPERATION

    The machine speed is determined by the load and fuel supply The generator voltage is determined by the excitation. For example, an increase in load will have two effects: Speed will initially fall because the energy being supplied by the fuel is less than that required by the load. The speed reduction is detected by the governor which opens the fuel valve by the required amount to maintain the required speed. Voltage will initially fall, the reduction is detected by the AVR which increases the excitation by the amount required to maintain output voltage

    PARALLEL GENERATORS

    When a machine operates in parallel with a power system, the voltage and frequency will be fixed by the system. The voltage regulator no longer controls the generator output voltage. The fuel supply to the prime mover which is controlled by the governor determines the power which is supplied by the generator .The generator excitation determines the internal emf of the machine and therefore affects the power factor. When excitation is increased above the level to achieve nominal no load voltage, rather than the voltage increasing, the reactive current flowing from the generator to the load increases resulting in a lagging pf condition on the generator. When the excitation is reduced below the level to achieve nominal no load voltage, rather than the voltage decreasing, the reactive current (vars) flowing to the generator from the load increases resulting in a leading pf condition on the generator.

  • General Arrangement of GT on skid 1. Reduction Gear box

    2. Air Inlet Duct Assembly

    3. Compressor Diffuser Combustor Assembly

    4.Turbine Assembly

    5. Exhaust Collector

    6.Compressor Assembly

  • Typical General Arrangement (SOLAR-Titan 130 Model)

  • Typical General Arrangement (SOLAR-Titan 130 Model)

  • Package Inside View (SOLAR-Titan 130 Model)

  • 3a -- Start System With Starting Motors and Gear BoxDriven Equipment

    Turbine can be accelerated by different ways likeA) Pneumatic start system is especially suited for gas turbine requirement and can use either gas or compressed air as a power source.

    B) Direct DC start system :- most common system which consist for a squirrel cage, three phase ac induction motors with variable frequency drive ( VFD) and engage/ disengage clutch coupled to gear box (Ref. Photo)

    C) Diesel/ Hydraulic start system:- consist of a skid mounted diesel fueled reciprocating engine which supplies power to drive a variable stroke hydraulic pump. The pump drives a hydrostatic motor connected to the turbine shaft via an overrunning clutch.Once the starter dropout speed is reached, the turbine continues to accelerate and overrun the starter through clutchTurbine Inlet CasingStartingMotorGear BoxCoupling Guard

  • 3b -- Typical Start Sequence1. Appropriate start and control systems are activated, the pre/post lubricating oil pump is started and, on verification of prelube pressure, the starter system is activated and begins turbine rotation.. 2. At about 21% speed, the ignition system and fuel valves are operated to admit and ignite fuel in the combustor. The heat of combustion and starter power accelerate the turbine. 3. At certain temperature, the ignition system is activated and acceleration continues. 4. At 66% (self-sustaining) speed, the start system is deactivated, the start counter registers an engine start, the hour meter begins to log engine operating hours, and the compressor variable vane control system activates and begins moving the vanes toward the maximum open position. 5. At 81% speed, the engine bleed valve control closes the bleed valve and the voltage regulator is activated, initiating generator, voltage build-up. 4 6. At 90% speed, generator output voltage and starting time are verified and the ready-to-load. timer is activated. 7. At 100% speed, the governor system assumes control of turbine speed. 8. At 90% speed plus 10 seconds, loading circuits are activated, enabling circuit breaker closure, and the ready-to-load indicator is illuminated.

    Chart2

    0.4

    20

    20

    20

    20

    20

    20

    35

    50

    65

    89.1

    Time (min.)

    Engine Speed (%)

    Typical GT start & Acceleration time line

    Sheet1

    050100150200250300350400450500

    0.420202020202035506589.1

    Sheet1

    0

    0

    0

    0

    0

    0

    0

    0

    0

    0

    0

    Time (sec.)

    Engine Speed (%)

    Typical GT start & Acceleration time line

    Sheet2

    Sheet3

  • 4a -- Fuel SystemA wide range of gaseous and liquid fuels are usedA) Gas Fuel System:-The gas fuel system includes all components necessary to control fuel at the proper schedule during starting and operation from no load to full load The principal components of the gas fuel system included with the package are: Gas strainer and fuel pressure switch Primary fuel valve Secondary fuel valve Gas fuel control valv Fuel control actuator Throttle valveB) Liquid fuel system : the major liquid fuel components are:- Boost pump (option) and strainer Duplex fuel filter (replaceable-element type) High pressure fuel pump High pressure filter Main fuel control valve Shutoff valve, bypass valve, purge valve, and torch valve Fuel manifold block, distribution lines and 12 fuel injectors

    C) Dual Fuel System:-The dual fuel system combines all the features of both the natural gas fuel system and the liquid fuel system previously described, and includes the controls for starting fuel selection and fuel changeover during operation. Switching from one fuel to the other can be accomplished under any load condition,

  • 4b -- Typical Gas fuel Supply System

  • 5 -- Lubrication SystemA standard lubricating oil system is designed to supply oil to engine bearings , gearbox and generator bearings.The system consists of a cooler, filter, main lube oil pump, pre/post lube oil pumps (AC), DC lube oil pump , lube oil vent separator ,regulating valves, as well as devices for protection against low pressure, low level, and high temperature. conditions. The oil tank is a reservoir incorporated into the base of the skid.

  • 6 -- Skid Enclosure With Ventilation System And Fire Fighting SystemThe Acoustic enclosure is fitted over the gas turbine and gearbox and mounted on the base skid. It is designed to achieve average package noise within limits.

    The ventilation fan, with inlet outlet filters and duct assembly provide both the cooling air to remove the heat radiated from the engine casing as well as maintaining the area classification in the event that the turbine is running on gas or highly liquid fuel.

    Enclosure frame work is provided with side door panels, lighting system, view glass, and fire fighting detection system including gas detectors, fire detectors, extinguishing discharge pipe work and nozzle.

    Fire and gas protection system includes an off skid fire extinguishing system like CO2 or water mist cabinet , discharge nozzle , and fire / gas detectors & pipe work. GT Enclosure Off Skid Fire Extinguishing Cabinet

  • 7 -- Turbine Control System

    The Turbotroric control system is a highly integrated programmable logic controller (PLC) based. control system with a video display terminal (VDT) and an operator interface panel

    The primary engine control functions, including speed, temperature and load, are accomplished by controlling the fuel input and the turbine variable geometry.

    The main control system inputs consist of the turbine speed transducer (magnetic pickup), a speed input module, turbine rotor inlet temperature thermocouples, a mill volt input module, current and potential transformer inputs, and an ac input module

    The control system maintains generator frequency and/or generator load distribution (when operating in parallel) by controlling turbine fuel flow by means of actuating fuel throttle valve.

    The microprocessor-based control system provides automatic starting, acceleration to operating speed, sequencing control, engine and generator monitoring during operation, and normal and malfunction shutdown

    Almost all control system uses an Allen Bradley Control Logic PLC.

  • C -- Gas Turbine PerformanceIn accordance with industrial standards, gas turbine performance is generally quoted at 15 deg C ambient temperature and sea level site condition , 60% relative humidity , and zero losses.In real world , however, ambient air temperature , site conditions , inlet exhaust pressure drop all have an impact on installed gas turbine site performance.

    Ambient Temperature:-typically rated power output with drop 0.3 to 0.5% for every 1deg F. rise in ambient air temperature.

    Elevation :- around every 1000 Ft increase in site elevation above sea level will see a 3.3 % reduction in the gas turbine power output.

    Inlet losses:- A 1 inch water gauge increase in inlet duct loss will sea an approximate 0.5 % reduction in power output and 0.1% increase in heat rate.

    Outlet losses :- A 1 inch increase in outlet duct and exhaust stack losses will see an approximate 0.15% reduction in power output and 0.1% increase in heat rate

    Turbine Performance Curves :-Performance for the engine is represented through a series of curves. This series generally consist of two turbine performance curves and two correction curves, is designed to encompass the majority of normal operating parameters required to trend the overall performance of the gas turbine engine. The turbine performance curves are based on the following standard conditions:Operation at sea levelZero inlet and exhaust duct system pressure losses Zero Compressor air bleedZero additional gas producer power extractionSpecified fuel at given LHV Relative Humidity 60 %

  • Typical Performance Curve For Engine Inlet Temperature

  • D Design Codes and Standards

  • E -- Toyo Scope and ResponsibilitiesSelection:- Selection of gas turbine package vender is done based on different parameters like Plant total electrical load requirement , Type and Availability of fuel , Starting requirements, Cost , After sale service , past experience etc etc.

    Procurement :-

    Detail Engineering :-

    Inspection and testing :- This mainly includes turbine engine performance test , package acceptance test , site test ( if applicable )

    Site Erecting and installation of Package :- ( by erection team )

    Commissioning :-

  • F GT Manufacture List


Recommended