GE Energy
HRSG – 101 TPSE – Dave Rogers, Rogers, Wulang Wulang Chriswin Chriswindarto darto
Date
What, Where, Why…?
What is an HRSG? Heat Recovery Steam Generator Wikipedia – ener energy gy recover recoveryy heat heat exchanger that recovers heat from a hot gas stream. It produces steam that can be used in a process (cogeneration plant) or used to drive d rive a steam turbine (combined cycle power plant)
It’s A Boiler…!!! 3 GE Internal - For internal distribution distribution only.
HRSG – More Than Just A Box of Tubes Overview
Operational Challenges on Installed Based BOP trips driven by HRSG accessories
Converts exhaust energy from gas turbine into steam
25% of forced outage hrs
Enables plant efficiency from 38% to 58%
Drum level issues cause trips preventing fast starts
$20-$25MM Parts $8-$9 MM Ship
Tube cracks and failures
$10 MM Field Assembly
are costly … critical path during outages
Modular assembly
Upgrades to GT often require HRSG analysis … potential showstopper 4 GE Internal - For internal distribution only.
Differences: HRSG vs Fossil Boiler HRSG uses exhaust gas (e.g. gas turbine) as a heat source and typically does not required a dedicated firing system HRSG do not use fans (draft is from gas turbine exhaust) HRSG generates steam at multiple pressure levels to improve heat recovery efficiency Heat transfer is typically by convection rather than radiation HRSG do not use membrane water walls HRSG uses finned tubes to maximize heat transfer HRSG typically has lower height profile & smaller footprint
Fossil Boiler 5 GE Internal - For internal distribution only.
Basic Components Water/ Steam Side: - Economizer/ Pre-heater (gas to heated water) - Evaporator & Drum (gas to boiling water to steam)
Gas out
- Superheater (gas to dry steam)
Gas Side: Inlet Duct, Baffles, Structural Steel, Casing, Insulation & Liner, Stack
Gas in
Accessories: - Silencers (gas & steam side) - Stack Damper & Bypass Stack Damper - Supplemental Fire/ Duct Burner
Evaporator
- Feedwater Pump
Superheater
- CO Catalyst & SCR System
Economizer
- Valves & Instruments
6 GE Internal - For internal distribution only.
In and Out t u O m a e t S H F R 0 & 5 0 P 1 H –
HP Drum
Height ~ 85’
% 0 8 d e F c u 0 d 8 e 1 r – t O u C O & s x a O G N
F 0 4 5 – t u O m a e t S P L
Stack Height ~ 150 – 200’
Integral Deaerator IP Drum
3 Pressure Level Reheater HRSG
50’
Gas in - 1100 F NOx CO
20’
Feedwater – 100 F
HP Superheater Reheater Duct Burner
HP Evaporator
SCR / CO Catalyst
IP Economizer IP Evaporator IP Superheater
GE Internal - For internal distribution only.
LP Economizer LP Evaporator LP Economizer
Length- ~ 100’ 7
Why HRSG is important? 3. Steam Turbine (ST):
1. Gas Turbine (GT): Converts Fuel
Converts Steam to
to Electricity and Waste Heat
Electricity
*Combined Cycle: A combination of thermodynamic Gas (GT) Cycle and Steam (HRSG & ST) Cycle in an Electrical Generating Power Plant to gain higher power output and efficiency
2. HRSG: Converts Waste Heat to Steam HRSG is the critical link between gas turbine and steam turbine in a combined cycle power plant 8 GE Internal - For internal distribution only.
9 GE Internal - For internal distribution only.
10 GE Internal - For internal distribution only.
Combined Cycle T-S Diagram Combined Brayton and Rankin Cycle Heat Source
T
COMBUSTION
E R U T A R E P M E T
E X P A N S I O N
GAS TURBINE TOPPING CYCLE N O I S S E R P M O C
HRSG
STACK
E X P A N S I O N
BOTTOMING CYCLE CONDENSER
Heat Sink
ENTROPY
S 5/
11 GE Internal - For internal distribution only.
Typical Energy Utilization Chart GT POWER (35.8%)
HRSG CASING LOSSES (0.5%)
ST LOSSES (1% ACCESORIES)
FUEL (100%) to Gas Turbine
EXHAUST HEAT (62.4%) to HRSG
GT LOSSES (1.8% ACCESORIES)
STEAM TURBINE (54.8%)
STACK LOSS (7.1%)
ST POWER (20.9%)
CONDENSER (32.9%)
Combined Cycles Systems (with HRSG & ST) Utilize More Fuel Energ y to Produce Useful Work Than GT Alone 12 GE Internal - For internal distribution only.
Design Philosophy
HRSG Design Philosophy Pinch Approach
e r u t a r e p m e T
Super Heater
T u r b i n e E x ha u s t G a s
HRSG design is a precise balance of the utilization of exhaust energy to produce steam energy in an economic way
Evaporator Economizer
Heat Duty Pinch Point The Difference Between Gas Temperature and Saturation Temperature at the Outlet of the Generating Bank Approach Temperature The Difference Between Economizer Discharge Temperature and Saturation Temperature
SH
EVAP ECON
The smaller the pinch and approach temperatures, the more efficient the HRSG, but also the more expensive the design 14 GE Internal - For internal distribution only.
HRSG Pinch Point Plot Steam and Water HP
1200
F ° F ° 800 e e r r u t u a t r e a p 400 r m e e p T m e 0 T
/ Reheat
IP LP
0%
20%
40%
60%
Percent Exhaust Energy Used Percent Exhaust Energy Used GE Internal - For internal distribution only.
80% 15
HRSG Types
HRSG Types Horizontal
Vertical
Once Through
• Horizontal gas flow direction
• Vertical gas flow direction
• Vertical tubes arrangement
• Horizontal tubes arrangement
• Either horizontal or vertical gas flow direction & tubes arrangement
• Majority installed
• Smaller footprint (historically common in Europe or outside US)
• Once Through eliminates the need of drum • Phase change from water to steam is free to move throughout the bundle • Theoretically more agile
17 GE Internal - For internal distribution only.
Product Features
Product Features
Finned Tubes
Internal insulation & Liner
Drum & Internals
Prevent heat losses, Provide outside casing temp of ~80 F
Is separated to produce dry steam
Steam & water mixture
Act as heat transfer/ exchanger medium Fins increase surface areas
Gas Baffles To Prevent Gas bypassing the heat exchanger
Duct Burner Supplemental firing to increase heat input for peak load Gas dP 0.25” w.c expected
SCR Systems
Burner Skid & Elements/ Runners
NOx reduction by ~ 86%
BMS-Burner Management System Flame Scanner
Gas dP 2-3” wc expected
Ignitor
Skid, Ammonia Based, Injection Grid, Catalyst
CO catalyst CO reduction by ~ 80% Gas dP ~ 1” wc expected
19 GE Internal - For internal distribution only.
Manufacturing
Manufacturing – Heat Transfer Section
Headers
Bare Tubes
Bare TuinSlit Fin Coil Coil Slit
Harps Assembly
ERW
Finned Tubes to header weld
Finned Tubes
Finned Tubes to header fit up
21 GE Internal - For internal distribution only.
Manufacturing – Casing, Insulation & Liner
22 GE Internal - For internal distribution only.
Manufacturing - Drums
23 GE Internal - For internal distribution only.
Field Assembly
HRSG – Typical Field Assembly
PLACE PO 1 - 2 Months
OBTAIN MATERIALS 2 - 3 Months
MANUFACTURE 7 - 9 Months
SHIP COMPONENTS 3 - 4 Months
ASSEMBLY 7 - 9 Months
COMMISSION 1 - 2 Months
Total Cycle Duration: 21 - 29 M onths
25 GE Internal - For internal distribution only.
HRSG- Degree of Shop Modularization
1. Harps
2. Modular
3. C-Frame
4. Full Assembly 26 GE Internal - For internal distribution only.
HRSG Life Cycle Issues & Opportunities
HRSG issues
Light and Heavy Ammonium Bisulfate Deposits
Considerations for Cycling Operation Component fatigue damage
GT Exhaust Non Uniform Flow
Chemistry control Attemperation Drum level control Sulfur dew point corrosion
Critical Components affected by Cycling HP Drum HP Superheaters RH Superheaters
Factors that impact fatigue damage GT Ramp Rates Pressure Management Heat retention during offline periods HRSG design & construction Flow Accelerated Corrosion (FAC) 28 GE Internal - For internal distribution only.
GE technologies applicable to HRSG
Metallurgy & coatings Creep, oxidation Thermal barrier Anticorrosion
Sensing and inspection Pulse eddy current, bore scope, high temp ultrasound, digital radiography etc.
Aeromechanics/CFD Bent fin tube CFD modeling
Performance improvement Gatecycle, eMap Acoustic cleaning
Life models Physics based & empirical lifing models
Water chemistry M&D Technology Monitoring, chemicals, Remote M&D chemistry models, 24/7 monitoring laboratory failure analysis etc. 29
GE Internal - For internal distribution only.
