Augu

st 2

013

MANAGER OF ENGINEERING, BLACK & VEATCH, SOUTH AFRICAKEVIN MILLER

HYBRID SOLAR THERMAL INTEGRATION AT EXISTING FOSSIL GENERATION FACILITIES

AGENDA

Solar Thermal Integration at Existing Rankine Cycle Generating Facilities [HYBRID CSP]

Solar Integration with Coal / Oil Steam Plants

2

Integrated Solar Combined Cycle adds steam to the Rankine Cycle

CONCEPTS OF COMBINED BRAYTON / RANKINE CYCLE GENERATION

3

Rankine CycleBrayton Cycle

• Steam produced from renewable source• Reduces use of natural gas or light oil• No additional capacity (MW) will result from

the operation of the solar thermal facility

HYBRID CONCEPTS OF INTEGRATED SOLAR THERMAL (ICSS)

4

5

Eskom CSP Workshop

More efficient with lower capitol cost

• Solar energy can be converted to electric energy at a higher efficiency.

• Capital costs are lower than for a CSP-only facility of similar size.

• Minimal additional plant staff is required• A hybrid plant does not suffer from the thermal

inefficiencies associated with the daily startup and shutdown of the CSP facility

• Potential reduction in fuel costs (fossil fuel input / MWh will decrease)

• Significant reduction in carbon emissions / MWh

WHY CONSIDER HYBRID CSP?

August 2013

6

Eskom CSP Workshop

• Located in area of high Direct Normal Solar Irradiation (DNI)

• Adequate space available• Allocation of approximately 2.75 Hectares / Mw

KEY CHARACTERISTICS OF CANDIDATE FACILITIES FOR ADDITION OF HYBRID CSP

August 2013

Eskom CSP Workshop

DIRECT NORMAL IRRADIATION (DNI)

August 2013

7

8

Eskom CSP Workshop

Black & Veatch was Owner’s Engineer on the addition of 75 MW of CSP steam generation at Martin Station• Area with high Direct Normal Solar Irradiation (DNI)• Available adjacent land area (202 hectare)• Available steam turbine capacity• Reduction in associated

fuel cost & carbon emissions

INTEGRATION OF CSP AT AN EXISTING GAS TURBINE COMBINED CYCLE FACILITY IN FLORIDA, USA

August 2013

9

Eskom CSP Workshop

MARTIN NEXT GENERATION SOLAR ENERGY CENTER

August 2013

Source; John Van Beekum for The New York Times

10

Eskom CSP Workshop

• Martin Next Generation Solar Energy Center was, until recently, the second largest solar-thermal facility in the world and the largest solar plant of any kind outside of California

• Facility may be the first hybrid facility in the world to connect a solar facility to an existing combined-cycle power plant

• Provides 75 megawatts of solar thermal capacity

• Designed to produce an average of 155,000 MWh of electricity annually

• The expected reduction of system-wide green-house gas emissions is projected to be approximately 2.75 million tons over a 30-year period

MARTIN NEXT GENERATION SOLAR ENERGY CENTER

August 2013

11

Eskom CSP Workshop

COMBINED CYCLE GENERIC LAYOUT

August 2013

HPSH

RH

HPEC

HPEC

IPSH

IPEC

LPSH

LPEC

Steam Turbine

Gas Turbine

Air

Fuel

Heat Recovery Steam Generator

Air-Cooled Condenser

LPEV

IPEV

HPEV

HPEC

HP IP / LP

LP Steam

Hot Reheat

Cold Reheat

Main Steam

IP SteamHP Steam

BFP

DuctFiring

12

Eskom CSP Workshop

• Admit Steam In LP Circuit• Admit Steam Into Cold Reheat• Admit Steam Into Hot Reheat• Admit Steam Into HRSG HP

Circuit Between Evaporator and Superheater

• Admit Main Steam

POTENTIAL SOLAR STEAM INJECTION POINTS

August 2013

The most efficient use of solar energy is displacing saturated steam production at the highest pressure.

The least efficient use of solar energy is feedwater preheating and steam superheating

13

Eskom CSP Workshop

Parabolic Trough Technology was selected by the Client

TYPICAL ACHIEVABLE STEAM TEMPERATURES

• Parabolic Trough• Fluid: Synthetic oil; HTF Temperature: 748ºF (398ºC)• Steam Temperature - ~715 F

• Central Receiver• Fluid: Steam, molten salt, air• Steam Temperature: 1025ºF (550ºC)

• Compact Linear Fresnel Reflector• Fluid: Steam• Steam Temperature: 520ºF (270ºC)

STEAM ADMISSION LOCATIONS DRIVEN BY SOLAR TECHNOLOGY

August 2013

14

Eskom CSP Workshop

Because parabolic trough systems are more mature commercially and technically.

• Trough Steam Admission Points:• LP, Cold Reheat, HP Steam Between Evap and

Superheater

• Power Tower Steam Admission Points:• Could be same as trough, but also allows higher

temperature admissions to Hot Reheat or Main Steam

• Compact Linear Fresnel Reflector• LP, Cold Reheat

STEAM ADMISSION LOCATIONS DRIVEN BY SOLAR TECHNOLOGY

August 2013

15

Eskom CSP Workshop

… but when it is being integrated into an existing facility, by the characteristics / capabilities of the existing steam cycle and equipment can become overriding considerations

STEAM ADMISSION LOCATIONS DRIVEN BY SOLAR TECHNOLOGY…

August 2013

16

Eskom CSP Workshop

Extraction point can impact the feedwater temperature further influencing the size of the solar field

• Boiler Feed Pump (BFP) Discharge• HP Economizer Exit with Booster Pump (A unique

booster pump may be needed to overcome the additional pressure drop on the HTF water / steam side)

TYPICAL FEEDWATER EXTRACTION LOCATIONS

August 2013

17

Eskom CSP Workshop

FEEDWATER FROM BFP DISCHARGE + HP STEAM ADMISSION USED IN THIS CASE

August 2013

HPSH

RH

HPEC

HPEC

IPSH

IPEC

LPSH

LPEC

Steam Turbine

Gas Turbine

Air

Fuel

Heat Recovery Steam Generator

Air-Cooled Condenser

LPEV

IPEV

HPEV

HPEC

HP IP / LP

Main Steam

HP Steam

BFP

DuctFiring

Solar Field / Solar Power Block

BFP Discharge

18

Eskom CSP Workshop

Other configurations are available, including vertical orientations

REPRESENTATIVE SOLAR STEAM GENERATOR OUTLINE

August 2013

HTF in

HTF out

• The vessel shown is ~ 15 meters long, 3 meters in diameter

• In this design there were (3) vessels for each GT / HRSG grouping; • Preheater • Steam generator (this vessel)• Superheater

Steam Out Steam Out

19

Eskom CSP Workshop

• Thermal lag time in solar fields is large, 30 minutes or more, due to the large volume of Heat transfer fluid (HTF) and variable HTF flow

• Cloud cover events result in changing HTF flow as the solar field responds to control HTF outlet temperatures

• As areas of the solar field see varying levels of cloud cover and the duration of the cloud passage is a variable, the degree the power plant output is impacted is dependant on the magnitude of these events

• Plants operating in regions with frequent cloud cover should consider these impacts into the design to mitigate operational impacts and to maximize daily solar utilization

SOLAR RESOURCE INTERMITTENCY

August 2013

20

Eskom CSP Workshop

• These events can lead to a shut-off of the solar steam generator train(s) (SSGs) if the HTF temperature falls near or below the saturation temperature of the steam supply generator (SSG) evaporators

• Unlike stand-alone solar plants, the steam pressure of the SSG is driven by the operating load of the CC plant CTGs, not the amount of steam that could be produced if the evaporator was free to slide in pressure

IMPACT OF CLOUD COVER ON SOLAR STEAM GENERATION (SSG) OPERATION

August 2013

21

Eskom CSP Workshop

MARTIN NEXT GENERATION SOLAR ENERGY CENTER

August 2013

Array includes 6,864 Units192,000 MirrorsCovers approximately 202 ha

SOLAR INTEGRATION WITH COAL / OIL STEAM PLANTS

22

23

Eskom CSP Workshop

TYPICAL STEAM PLANT GENERIC SCHEMATIC

August 2013

Condenser

HP IP/LP

Cold Reheat

Steam Turbine

LP FW HeatersHP FW Heaters BFP

Deaerator

Final Feedwater

Main Steam

Hot Reheat

CondensatePump

Steam Generator(BOILER)

Generator

24

Eskom CSP Workshop

CONFIGURATIONS CAN INCLUDE THE FOLLOWING, ALONE OR IN COMBINATION• Feedwater heating - External heating• Feedwater heating – Provide heating steam• Generation of Cold Reheat Steam• Generation of Hot Reheat Steam• Generation of HP steam • Generation of Main Steam

POTENTIAL INJECTION POINTS FOR SOLAR-SOURCED THERMAL ENERGY

August 2013

26

Eskom CSP Workshop

Criteria used in the selection of the solar technology used in a specific plant should include not only the capabilities of the candidate technology, but the steam cycle and characteristics of the existing steam cycle

• Candidate Trough Steam Admission Points:• Feedwater Heating, LP, Cold Reheat, HP Steam Between

Evap and Superheater

• Candidate Power Tower Steam Admission Points:• Could be same as trough, but also allows higher

temperature admissions to Hot Reheat or Main Steam

• Candidate Compact Linear Fresnel Reflector• Feedwater Heating, LP, Cold Reheat

STEAM ADMISSION LOCATIONS DRIVEN BY SOLAR TECHNOLOGY

August 2013

27

Eskom CSP Workshop

EXTERNAL FEEDWATER HEATING

August 2013

Air-Cooled Condenser

HP IP / LP

Cold Reheat

Steam Turbine

LP FW HeatersHP FW Heaters BFP

Solar Field / Solar Feedwater Heaters

Deaerator

Steam Generator

Final Feedwater

Main Steam

Hot Reheat

CondensatePump

28

Eskom CSP Workshop

GENERATION OF HP STEAM

August 2013

Air-Cooled Condenser

HP IP / LP

Cold Reheat

Steam Turbine

LP FW HeatersHP FW Heaters BFP

Solar Field / Solar Steam Generators

Deaerator

Steam Generator

Final Feedwater

Main Steam

Hot Reheat

CondensatePump

HP Steam to HP Superheater

30

Eskom CSP Workshop

• Hybrid Solar thermal has been applied on large scale basis at an existing combined cycle facility

• The concept has proven to be operationally acceptable• Application at existing coal or oil-fired facilities is

technically feasible• Designs must consider the steam cycle, where addition

of solar generated energy is physically possible, as well as the required temperature and pressure requirements of the cycle

SUMMARY

August 2013

www.bv.com