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

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 2015 Heat Rate Conference 2

Manual Feed vs. Automatic H2 Control 2015 Heat Rate Conference 3

Pressure Setpoint: 30 PSIG Alarm Setpoint: 25.5 PSIG 2015 Heat Rate Conference 4

Over time: Purity Drops H2 Input Purity of 99.5% 2015 Heat Rate Conference 5

Over time: Dewpoint Higher 2015 Heat Rate Conference 6

Automatic Closed Loop Advantages 2015 Heat Rate Conference 7

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 2015 Heat Rate Conference 8

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 2015 Heat Rate Conference 9

H2 Pressure and Purity Control 2015 Heat Rate Conference 10

Windage Loss Reduction vs. H2 purity 11 2015 Heat Rate Conference

H2 Purity Test: Endesa 12

Dynamic H2 Pressure Control 2015 Heat Rate Conference 13

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 % 2015 Heat Rate Conference 14

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 % 2015 Heat Rate Conference 15

Use Generator Loss Indicator to Determine Optimum 2015 Heat Rate Conference 16

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 2015 Heat Rate Conference 17

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 2015 Heat Rate Conference 18

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. 2015 Heat Rate Conference 19

Bar Placement and Effect Triangle Gradation Bar Placement and Effect 20

Benefits 21

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. 2015 Heat Rate Conference 22

Hydrogen Control System Benefits Decreased dewpoint in the generator case protects winding insulation and reduces corrosion. Decreased average P may reduce stress on seals 2015 Heat Rate Conference 23

Potential Cost Savings Avoid capital and maintenance costs for: No dryer No Compressor (if Low P storage) 2015 Heat Rate Conference 24

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 2015 Heat Rate Conference 25

For more info. contact: Brad Radl Taber International Office:  440-286-1319 radl@taber-intl.com www.taber-intl.com www.griffinopensystems.com