Date post: | 04-Jun-2018 |
Category: |
Documents |
Upload: | gauravbgprocks6357 |
View: | 215 times |
Download: | 0 times |
of 22
8/13/2019 28997507-Gas-Turbine
1/22
GAS TURBINE
PRINCIPLE :-- Fluid is drawn into the compressor
and after compression passes to a combustion
chamber. Energy is supplied in the combustionchamber by spraying fuel into the fluid stream, and the
resulting hot gases expand through turbine. In our case
working fluid is atmospheric air.
Gas turbine operates on the principle of Brayton cycle.
8/13/2019 28997507-Gas-Turbine
2/22
TURBINE
COMPRESSOR
COMBUSTIONCHAMBER
COOLING
T
EM
P
ENTROPY
P
R
ES
S
U
R
EVOLUME
COMBUSTIONCHAMBER
TURBINECOMPRESSOR
COOLING
BRAYTON CYCLE
1
2 3
4
1
2
3
4
8/13/2019 28997507-Gas-Turbine
3/22
CC
GD
AIR
IND-DIESEL ENGINE
CC-COMBUSTION CHEMBER
G-GENERATOR
FUEL
EXHAUST
GAS TURBINE
8/13/2019 28997507-Gas-Turbine
4/22
BLOCK DIAGRAM OF GAS TURBINE
DIESEL
ENGINE
ACC.
GEAR
MAIN
COMP.TURBINE
BOOSTER
COMPRESSOR
TORQUE
CONVERTORRATCHET
JAW
CLUTCH
ATOM.
AIR
COMP.
FUEL
PUMP
MOP MHOP
AIR FILTERFUEL
COMBUSTION
CHAMBER
GENERATOR EXITOR
BYPASS
STACK
DIVERTOR
DAMPER
HRSG
8/13/2019 28997507-Gas-Turbine
5/22
FUNCTIONS OF VARIOUS MAJOR COMPONENTS
DIESEL ENGINE: ---
It is required to supply a high torque at the time of starting to drive the
turbine upto the firing speed and then fire turbine to reach self sustainingspeed. It also drives the start up compressor till the main compressor
comes into the service.
TORQUE CONVERTOR:---
It is used to provide the required torque and speed for thecranking of the turbine.
RATCHET:----
The ratcheting system is provided for rotating the shaft either before
start up or after the shutdown of the machine.
JAW CLUTCH:---
The function of jaw clutch is to engage/disengage diesel engine to
gas turbine.
8/13/2019 28997507-Gas-Turbine
6/22
ACCESSORY GEAR BOX:----
Accessory gear box performs the following multiple functions.
1) To drive the various accessories at their designed speed and requiredtorque.
2) To connect and disconnect the tubine from the starting device.
3) To trip the turbine mechanically through over speed bolt mechanism.
VARIOUS COMPONENT DRIVEN BY ACCESSORY GEAR BOX ARE.
A) Main Hydraulic Oil Pump (MHOP).
B) Main Lube Oil Pump (MOP).
C) Main Atomising Air Compressor.D) Fuel Oil Pump.
8/13/2019 28997507-Gas-Turbine
7/22
AIR INLET SYSTEM:---- It is required to provide clean air to the compressor from the
atmosphere. The atmospheric air passes through a set of
filter element and then to the inlet plenum of the main air
compressor.MAIN AIR COMPRESSOR:--- Compressor is axial flow type with 17 stages. The
compressor suction recieves clean air from the air
inlet system. The compressed air is used in GT for
the various purposes as described below.
A) Combustion of fuel in combustion chamber.
B) Cooling of various turbine parts.
C) Sealing of oil in bearings.
D) Purging of air filters.
INLET GUIDE VANES(IGV):---It is located at the after end of inlet casing. Theposition of these vanes controls the quantity of
compressed air flow. Vanes are actuated by a
hydraulic cylinder connected to the control ring
that turn the individual pinion gears mounted at
the end of each vane.
8/13/2019 28997507-Gas-Turbine
8/22
COMBUSTION SECTION:--- The combustion system is reverse flow type. The high
pressure air from the compressor reverses its path in the
transition pieces and then move to the annular spaces
that surround each of ten combustion chambers.
EACH COMBUSTION CHAMBER HAS THE FOLLOWING MAIN PARTS:----
a) Nozzle Flow Sleeve
b) Liner
c) Transition Pieced) Cross Fire Tube
e) Spark Plug (2 nos.)
f) Flame Detectors(2nos.)
FUNCTIONSOF VARIOUS PARTS
A) TRANSITION PIECES:--- It directs the hot gases from the liner to turbine nozzle.
B) NOZZLE:--- It disperses and mixes the fuel with proper amount of combustion air.
C) CROSS FIRE TUBE:--- A passage to propagate the flame from one combustion
chamber to another after the initiation of fire by spark plug.
D) COOLING OF LINER WALL:--- A film of main compressor discharges air shields
8/13/2019 28997507-Gas-Turbine
9/22
E) COMBUSTION CHAMBER:---
In the combustion chamber, hot combustion gases
from the reaction zone passes to the dilution zone where additional
amount of air is mixed to bring the temp. of hot gases to desired level.
F) SPARK PLUG:---Combustion is initiated by the spark plugs provided in two
combustion chambers when the firing command is given by the
Mark - V. The spark plug operates at the voltage of 11 KV & this
high voltage is supplied by ignition transformer.
G) ULTRA VIOLET FLAME DETECTOR:---During the starting sequence, it is essential that indication of
presence or absence of flame in the combustion chambers be
transmitted to the Mark-V. The two nos. flame detectors are
provided in combustion chamber no. 7 & 8 to meet the purpose.
H) FUEL NOZZLES:---Each combustion chamber has one nozzle & each nozzle has four
inlets for Natural Gas, liquid fuel, Purge air & atomising air. The
liquid is atomised by means of atomising air. The swirl tip in the
nozzle imparts a swirl in the combustion air for complete
combustion and resulting in the smoke free operation of the unit.
8/13/2019 28997507-Gas-Turbine
10/22
TURBINE:---
The turbine has two stages. Turbine section is the area in which heat
heat energy in the form of pressurised hot gases produced by the
compressor and combustion sections is converted into the mechanicalenergy. The main parts and features of turbine are described below.
A) COOLING OF BUCKETS:---
As the first stage bucket are the first to encounter the extremely hot
gases, hence longitudinal holes are provided in these buckets for cooling
as air is passes through holes.
B) TURBINE ROTOR COOLING:---
Rotor cooling is done by means of a positive flow of cool air radially
outward through a space between the wheel and the buckets, then through
the stator and finally in to the main gas stream area which is called wheel
space.C) FIRST STAGE WHEEL SPACE COOLING:---
The forward wheel space cooling is done by compressor discharge air
which is leaking through the labyrinth. This air discharges in to the main
gas stream. The aft wheel space is cooled by 2nd stage nozzle cooling
air.
8/13/2019 28997507-Gas-Turbine
11/22
D) SECOND STAGE WITH SPACE COOLING:---
Forward wheel space is cooled by leakage from Ist stage aft wheel
space through the inter stage labyrinth. Aft wheel space is cooled byair from the internal extraction system. This air enters the wheel
space through slots in the forward face of the spacer.
8/13/2019 28997507-Gas-Turbine
12/22
SPECIFICATION OF GAS TURBINEAIR COMPRESS0R
1. NO OF STAGES : 17
2. TYPE : AXIAL FLOW
3. CASING SPLIT : HORIZONTAL
4. COMPRESSION RATIO : 1:10.3
5. RATED SPEED : 5100 RPM
6. EXTRACTION : 4th, 10th & 17th STAGE FOR COOLING,
SEALING & AIR FILTER, PULSE CLEANIG.TURBINE
1. NO OF STAGES : 2
2. TYPE : IMPULSE
3. CASING SPLIT : HORIZONTAL
4. MINIMUM CONTINUOUS
SPEED : 4896 RPM
5. IGNITION SPEED : 940 RPM
6. SELF SUSTAING SPEED : 2640 RPM
7. MECHANICAL TRIP SPEED : 5737 50
8. ELECTRICAL TRIP SPEED : 5610 +30
8/13/2019 28997507-Gas-Turbine
13/22
COMBUSTION SYSTEM
1. TYPE : REVERSE FLOW
2. NO OF COMBUSTER : 10
3. NO OF FUEL NOZZLE/
COMBUSTERS : 1
4. TYPE OF IGNITORS : AUTOMATIC RETRACTING TYPE
5. NO OF IGNITORS : 26. NO OF FLAME DETECTORS : 2
7. TYPE OF FLAME DETECTORS : ULTRA VIOLATE
8. FIRING TEMP. AT BASE LOAD : 963C AT TRAILING EDGE OF 1st
STAGE NOZZLE.
9. FIRING TEMP. AT PEAK LOAD : 996C.
8/13/2019 28997507-Gas-Turbine
14/22
ISO OUTPUT WITH NG : 26.3 MWIS0 OUTPUT WITH DISTILLATE : 25.8 MW
HSD & NAPTHA : FUEL FOR GT & HRGS.
HEAT RATE WITH NG : 3021.5 KCAL/KWH
HEAT RATE WITH DISTILLATE : 3041.5 KCAL/KWH
8/13/2019 28997507-Gas-Turbine
15/22
USED HEAT
ENERGY
REJECTED
ENTROPY CHART
HEAT ENERGY
ENTROPY
T
E
MP
E
R
AT
U
R
E
8/13/2019 28997507-Gas-Turbine
16/22
EFFECT OF INCREASED
BACK PRESSURE
USED HEAT
ENERGY
REJECTED
HEAT ENERGY
T
E
M
P
E
R
A
TU
R
E
ENTROPY
8/13/2019 28997507-Gas-Turbine
17/22
EFFECT OF INCREASED STEAM
TEMPERATURE & PRESSURE
T
E
MP
E
R
AT
U
R
EENTROPY
USED HEATENERGY
REJECTED
HEAT ENERGY
8/13/2019 28997507-Gas-Turbine
18/22
EFFECT OF REHEAT ON
CYCLE EFFICIENCY
T
E
M
PE
R
A
TU
R
E
ENTROPY
USED
HEAT ENERGY
ADDITIONAL HEAT
INPUT IN THE
REHEATER
REJECTED
HEAT ENERGY
8/13/2019 28997507-Gas-Turbine
19/22
T
E
MP
E
R
A
T
U
R
E
ENTROPY
1
2
3
4
GAS TURBINE CYCLE
USED HEAT
ENERGY
REJECTED
HEAT ENERGY
8/13/2019 28997507-Gas-Turbine
20/22
T
E
MP
E
R
A
T
U
R
E
ENTROPY
1
2
3
4
USED HEAT
ENERGY
REJECTEDHEAT ENERGY
GAS TURBINE & HRSG
COMBINE CYCLE
COMPARISON OF GT & STG
8/13/2019 28997507-Gas-Turbine
21/22
SLN0 GAS TURBINE STEAM TURBINE
1 EFFICIENCY SIMPLE CYCLE = 29% TURBINE CYCLE=30%
CO-GENERATION= 85%
2 GESTATION PERIOD LOW(18 MONTHS) HIGH (30 MONTHS)
3 LIFE AROUND 10 YRS. THEN 20 TO 25 YRS.
REQUIRES MAJOR MAINT.
4 MAINTENANCE COST HIGH LOW5 OPERATION COST LOW HIGH6 STARTING TIME LESS( 12 TO 15 MIN) MORE ( 1 TO 2 HRS. )
7 GOVERNOR MICROPROCESSOR BASE HYDRAULIC
8 AUXILIARIES/UTILITY LOW HIGH
9 EMISSION ( Nox, Sox ) LOW HIGH
COMPARISON OF GT & STG
GAS G
8/13/2019 28997507-Gas-Turbine
22/22
GAS TURBINE TRIPPINGPARAMETERS UNITS
1 LUBE OIL HEADER PRESSURE LOW 0.7 kg/cm2
2 LUBE OIL HEADER TEMPERATURE HIGH 78 degree C
3 BEARING VIBRATION HIGH 25.4 mm/sec
4 EXHAUST GAS TEMPERATURE HIGH TTRBXB + 22
5 EXHAUST DUCT PRESSURE HIGH 12" WC
6 INLET DUCT PRESSURE 8" WC
7 FUEL GAS PRESSURE LOW 13 bar
8 TURBINE OVERSPEED 110%
9 TRIP OIL PRESSURE LOW 1.3 kg/cm2
10 FLAME FAILURE
11 LOSS OF FUEL
P