Post on 07-Nov-2014
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SELECTING THE OPTIMISED PUMP CONFIGURATION AND DRIVE OPTION FOR THE
CONDENSATE EXTRACTION AND BOILER FEED PUMPS FOR THE NEW ESKOM SUPERCRITICAL POWER STATIONS
Willem van der WesthuizenCorporate Pump Consultant
andGugu Ngcobo
Mechanical Engineer
Eskom Group TechnologyJohannesburg,
South-Africa
2011/05/13 2
ABSTRACT• Eskom has embarked on a major Capital Expenditure program to cater for
the growing demand for power as a result of a rapidly developing South African economy.
• Future developments include electrical power generation utilizing diverse technologies such as; – Fossil– Nuclear– Pebble Bed Modular Reactors– Hydro, Open Gas Cycle – Combined Cycle – Wind and Solar Energy
• The first two new Supercritical Fossil fired Power Stations, Medupi (6 Units, each 794 MW) and Kusile (6 Units, each 798 MW) are presently in the design and construction phase.
• The condensate extraction pumps and boiler feed pumps are amongst the highest consumers of auxiliary electrical power within a power station, it is therefore of utmost importance that the correct optimized pump configurations and drive options for each of these pumps is selected.
2011/05/13 3
Background to Eskom• Eskom, South Africa’s electricity utility:
• Is one of the top 10 utilities in the world by generation capacity
• Generates approximately 95% of electricity used in South Africa
• Generates approximately 45% of electricity used in Africa
• Number of employees, 37 857
• Electricity sales, 214 850GWh
• Nominal capacity, 44 193MW
• Net maximum capacity, 40 503MW
• Power lines and cables (all voltages), 381 700km
• Carbon dioxide emissions, 221,7Mt
• Total water consumption, 323 190ML
2011/05/13 4
2011/05/13 5
2010
2011/05/13 6
2010
2011/05/13 7
Capacity Expansion –Driven By Long Term Demand Forecast
Long term forecasts - national + foreign
30000
40000
50000
60000
70000
80000
90000
2005 2010 2015 2020 2025
MW
PositionModerate Eskom position based on
4% growth electricity growth supporting 6%
economic growth
77960 MW
56710 MW
Eskom moderate position 2.3% electricity
growth basedeconomic growth of 4%
Hydro
Nuclear
Oil/Gas
Power Purchase
Coal
Transmission
Renewables (Wind, Solar)
Eskom Capacity Projects Funnel [Gross Mwe]
Research PrefeasibilityFeasibility, Business
Case Study
BuildProgramme
In Operations
Opportunity Screening
165
PBMR
100
Concentrating
Solar Tower
1200
Discard Coal
1000
CBM Botswana
1000
Monontsa PS Lesotho
4800
Coal-3
4800
Coal-4
600
Moambo
Moz-Gas600
Kafue Lower Zambia
1300
Mphanda Nkuwa Moz
1200
Mmamabul Botswana
1500
Moatize Moz
400
OCGT Conversion
750
Komati
4764
Medupi
4800
Kusile
800
Grootvlei
746
Gourikwa
1337
Ankerlig
1352
Ingula
2100
Co-Gen MTPPP
International
Projects (Imported Power)
200
Arnot upgrade Phase I
1600
Camden
300
IGCC
400
Gr’tvlei
1800-5400
Coal-5
600
Maropule Botswana
1000
Mmamantswe Botswana
CCS
Carbon Capture
xx
Wave /Ocean current Energy 30-70
Or River Nam-RSA
360
KNBE Zambi
a
360
KSB Zimbabwe
1500
Pumped
Storage-D
n x 3200
Nuclear- n
Other KnownOpportunities
2000
Benga Mozambique
35
Massingir Moz
180
Lurio Moz
4500
MultiSite IPP
1600
Batoka Gorge Zim / Zam
1400
Gokwe N Zimbabwe
1000
Lebombo Swaziland
6700
Kwanza Angola
1000
DME IPP Peaker
60
Peaker Moz
500
Wind 2
540
HFO n x 300n x 800
Coal-n
Tx
Mazambique
Back-Bone
AC/DC
Note: Power import for most of the regional projects will be lower than the stated capacitydue to host country off-take
4,533 MW12, 566 MW20,680 MW18, 800 MW+ n x 3200 MW nuc.
250
Komati
100
Sere-Wind 1
3300Nuclear
(delayed)
2100
UCG
500
CBN Moz
3500
Inga III Westcor
1500
Tubatse (delayed)
nx400
CCGT nx100
Wind_Fleet
nx150
OCGT
100
Arnot upgrade Phase II
2011/05/13 9
Two new Supercritical Power Stations• The first two new Supercritical Fossil fired Power Stations,
Medupi (6 Units, each 794 MW) and Kusile (6 Units, each 798 MW) are presently in the design and construction phase.
• Both power stations have Air Cooled Condensers• The Turbine contact was awarded to Alstom and the Boiler
contract to Hitachi.• The condensate extraction pumps and boiler feed pumps
are amongst the highest consumers of auxiliary electrical power within a power station, it is therefore of utmost importance that the correct optimized pump configurations and drive options for each of these pumps is selected.
2011/05/13 10
Matimba Power Station 6x660 MW
Kendal Power Station 6x680 MW
2011/05/13 11
Progress at Medupi Power Station
Medupi and KusilePower Station
Condensate Extraction Pump
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Condensate Extraction Pump• All existing Eskom Power Stations utilize a 2 x 100%
Condensate Extraction Pump (CEP) configuration.• The older type Power Stations that don’t have any
Main Turbine bypass systems utilizes two fixed speed CEP’s with their design point the same as the Turbine Maximum Continuous Rating (TMCR) duty point.
• The pumps are horizontally split casing designs with a double entry suction impeller.
• The slow speed and double suction impellers are specifically considered in order to satisfy the NPSH requirements of the pumps.
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Condensate Extraction Pump• On our newer larger plants with an output of
greater than 500MW, where the condensers are larger and the pump flow greater, the condensate extraction pumps are vertical multistage with the pump element mounted in a suction can which is connected directly to the hot - well of the condensers.
• All the power stations, whose outputs are greater than 500 MW per Unit, have Main Turbine Bypass Systems.
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350 kW
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Condensate Extraction Pumps for Medupi and Kusile P/S’s
Option 1:• 2 x 100 % Vertical Spindle CEP’s
–One variable speed–One fixed speed
Option 2:• 2 x 100 % Horizontal arrange CEP’s
–One variable speed–One fixed speed
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Condensate Extraction Pumps
Horizontal CEP preferred• Simple design• Easier maintenance• Spares holding less
2011/05/13 20
Condensate Extraction PumpsPosition of CEP• Below ACC Condensate Tank• Optimum suction or NPSH available to CEP• Enclosed in a dedicated CEP building• Traveling Crane and maintenance area
provided for in building• CEP Electrical system incorporated with
ACC sub-station
2011/05/13 21
Medupi and Kusile
Boiler Feed Pump Drive Options
2011/05/13 23
Boiler Feed Pump Drive Options
• Drive options technically acceptable
1. High Speed VSD E-Motor (with low speed gearbox)
2. Low Speed VSD E-Motor (with high speed gearbox)
3. Fixed Speed Motor & Voith Vorecon
4. Fixed Speed Motor & Voith Hydraulic Coupling
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Boiler Feed Pump Drive
Booster pumpMain pump
Filter
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1. High Speed VSD Electric Motor with Speed Reduction Gearbox
Booster pumpMain pump
Filter
Speed Reduction Gearbox
High Speed VSD
Electric Motor
N = 1500 rpmN = 6000 rpm
BFP set efficiency = 81.2 %
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Speed Increase Gearbox
2. Low Speed VSD Electric Motor with Speed Increase Gearbox
Booster pump Main pump
Filter
Low Speed VSD
Electric Motor
N = 1500 rpm N = 6000 rpm
BFP set efficiency = 79.9 %
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3. Fixed Speed Electric Motor with Voith Vorecon Planetary Geared Variable Speed Fluid Drive Coupling
Booster pump Main pump
Filter
Voith Vorecon Planetary Geared
Variable Speed Fluid Drive Coupling
Fixed Speed
Electric Motor
N = 1500 rpm N = 6000 rpm
BFP set efficiency = 77.2 %
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4. Fixed Speed Electric Motor with Voith Variable Speed Fluid Drive Coupling
Booster pumpMain pump
Filter
Voith Variable Speed
Fluid Drive CouplingFixed Speed
Electric Motor
N = 1500 rpmN = 6000 rpm
BFP set efficiency = 70.2 %
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BFP Drive BFP Set Efficiency %
*Power Consumption kW Capital Cost
%High Speed VSD E-Motor + LS Gearbox 81.2 24274.8 203
Low Speed VSD E-Motor + HS Gearbox 79.9 24685.2 161
Voith Vorecon Mechanical VSD 77.2 25520.84 133
Voith Hydraulic Coupling 70.2 28103.1 100
Efficiencies of BFP Drive Options
*Power Consumption = 2 pumps @ TMCR
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Economic Evaluation• Two models were used
– Official Generation EE model– ..\..\..\BFP Drive Options vs. Load Profile rev2.xls
– Eskom Enterprise Engineering – Steag/EvonicHybrid Model
– ..\..\BFP Economic Evaluation.xls
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Capital Costs of BFP Drive Options and EE results
BFP Drive Capital Cost in R M per unit for 3 BFP sets
Capital Cost %
EE ResultsLevelised costs
R/MWh
High Speed VSD E-Motor + LS Gearbox - 203 187.11
Low Speed VSD E-Motor + HS Gearbox
- 161 186.66
Voith Vorecon Mechanical VSD - 133 186.50
Voith Hydraulic Coupling - 100 186.73
1
2
3
4
2011/05/13 32
BFP Load vs Pump set Efficiency
40
50
60
70
80
90
50 60 70 80 90 100 110
Pump Load
Pum
p se
t Effi
cien
cy
High speed VSD % Low speed VSD % Vorecon % Voith %
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Boiler Feed Pump Power Requirement
4000
6000
8000
10000
12000
14000
16000
40 50 60 70 80 90 100 110
Pump Load
Pow
er A
bsor
bed
(kW
)
Pump shaft power Booster + Main Motor Input Power High Speed VSDMotor Input Power Low Speed VSD Motor Input Power VoreconMotor Input Power Voith
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SES Meliti P/S 350 MW – Florina Greece
2011/05/13 35
Mannheim P/S – 9 MW Vorecon BFP Drive
2011/05/13 36
Boiler Feed Pump Train LayoutABB Electric Motor
Power = 19 700 kW
Speed = 1482 rpm
Weight = 48 000 kg
VOITH VORECON RW16-145 F9
Output Power = 16 192 kW
Output Speed = 5770 rpm
Weight = 45 000 kg
Main Pump HPT 350-370-6s/29A
Pressure = 275 Bar
Flow = 354 l/s
Temperature = 183 oC
Speed = 5665 rpm
Weight = 14 000 kg
Booster Pump
Pressure = 16 Bar
Flow = 354 l/s
Temperature = 183 oC
Speed = 1482 rpm
Weight = 4 500 kg
2011/05/13 37
Closing Note!• When selecting an optimised critical pump
configuration and drive option installed in a Power Plant the following need to be considered:
Power Station Operation modeCapital cost of complete pump drive trainPump set efficiency and auxiliary power absorbedAuxiliary power costSelection of proven technology and equipment with high reliability and availability
2011/05/13 38
COMMITMENT !
“If our reference list increase
with 36 – 19 MW Vorecons
We will just have to make it work! “
– Dr. Juergen Zeschky - VOITH
Thank You