1. 2015 EPRI Heat Rate Conference
Closed Loop Optimization of H2 Pressure and Purity for Improved Heat Rate
2015 EPRI Heat Rate Conference
Houston, Texas
Author: Brad J. Radl, Taber International, LLC
2015 Heat Rate Conference

2. Why are we using H2 for cooling
Minimize Loss due to Windage
Maximize Generator Output
Efficient Heat Transfer
Keep Generator Internals Clean
Minimize issues associated with corrosion
Minimize issues associated with aging
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3. Manual Feed vs. Automatic H2 Control
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4. Pressure Setpoint: 30 PSIG Alarm Setpoint: 25.5 PSIG
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5. Over time: Purity Drops
H2 Input Purity of 99.5%
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6. Over time: Dewpoint Higher
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7. Automatic Closed Loop Advantages
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8. Hydrogen Purity Reduces Windage Loss
Direct improvement in kW for same torque
Or assuming ~33% efficient unit, coal consumption saving will be 3x the generator efficiency gain.
Improved heat removal
Less heat stress from variance in Pressure and Purity
Reduce or eliminate any temperature alarms in generator casing
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9. H2 DewPoint Reflects water and hydrocarbon accumulation in cooling gas
Lower Dewpoint results in lower windage loss
Lower Dewpoint results in lower corrosion of generator components
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10. H2 Pressure and Purity Control
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11. Windage Loss Reduction vs. H2 purity11
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12. H2 Purity Test: Endesa 12

13. Dynamic H2 Pressure Control
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14. Windage Loss Reduction Per 630MW unit
8000
Typical Operation
99.7% Purity
75 psig
Losses = 4000 kw
Windage Loss in KW’s
6000
75 psig
60 psig
45 psig
Proposed Operation
99.7% Purity
60 psig
Losses = 2500 kw
4000
2000 90 92 94 96 98
100
Hydrogen Gas Purity in %
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15. Windage Loss Reduction 1.5 MW Per 630MW unit
8000
Typical Operation
97.5% Purity
60 psig
Losses = 4000 kw
Windage Loss in KW’s
6000
75 psig
60 psig
45 psig
Proposed Operation
99.5% Purity
45 psig
Losses = 2500 kw
4000
2000 90 92 94 96 98
100
Hydrogen Gas Purity in %
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16. Use Generator Loss Indicator to Determine Optimum
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17. Trade-Offs Lower H2 Pressure – less heat removed by gas
Lower H2 Pressure – less heat generated by windage
Lower H2 Pressure – less aux power to ‘push’ H2
Heat in Generator (raised or lowered) affects
Aging of organic material
Core and Misc. Losses
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18. Proposed Taber – Project
Calculates Thermal Load removed by H2 coolers
Calculates Required H2 Pressure vs. Load curve and determines optimum setpoint curve with margin.
Uses demand signal to anticipate load changes.
High deadband requirements to make a pressure change.
Tracks over time any shifts in the thermal load versus MW output
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19. Proposed Taber – Project
Best Target Unit would have load band type of operation
Allows H2 pressure to drop at night through purposeful purging
Anticipate and respond to load rises during day and increase H2 P to keep generator cool.
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20. Bar Placement and Effect
Triangle Gradation
Bar Placement and Effect 20

21. Benefits 21

22. Improve Generator Efficiency
Increased average H2 purity
Lower average H2 pressure levels
----> reduce windage loss, reduce aux power
Depending on initial conditions and load profile, could lead to 0.1% to 0.5% eff. Improvement or ~0.3% to 1%+ HR gain.
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23. Hydrogen Control System Benefits
Decreased dewpoint in the generator case protects winding insulation and reduces corrosion.
Decreased average P may reduce stress on seals
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24. Potential Cost Savings
Avoid capital and maintenance costs for:
No dryer
No Compressor (if Low P storage)
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25. Summary
Automation of manual operation for controlling H2 should lead to:
Fewer alarms in control room
Heat rate efficiency gain
Lower long term maintenance costs for generator
Opportunities for diagnostic information
Project Needs a Home
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26. For more info. contact:
Brad Radl Taber International Office: