Supercritical Carbon Dioxide Power Cycle Development Overview

Supercritical CO2 Power Cycles Symposium September 9-10, 2014

The 4th International Symposium – Supercritical CO2 Power Cycles

Technologies for Transformational Energy Conversion

September 9-10, 2014, Pittsburgh, Pennsylvania

Supercritical Carbon Dioxide Power Cycle Development Overview

Kenneth J Kimball

BMPC, Knolls Atomic Power Laboratory

P.O. Box 1072, Schenectady, NY 12301-1072

Ken Kimball has been actively involved with supercritical CO2 Brayton power cycle development since 2005 working at the Knolls Atomic Power Laboratory in Schenectady, NY, USA. This effort has included working closely with numerous University, National Laboratory and Industry groups. He has a BS degree in mechanical engineering from Worcester Polytechnic Institute and an MS degree in mechanical engineering from Rensselaer Polytechnic Institute. He has previously presented development progress at the Supercritical CO2 Brayton power cycle development symposiums in 2009 and 2011 and the ASME Turbo Conferences in 2012 and 2013.


Abstract

Bechtel Marine Propulsion Corporation (BMPC) is testing a supercritical carbon

dioxide (S-CO2) Brayton system at the Bettis Atomic Power Laboratory. The 100

kWe Integrated System Test (IST) is a two shaft recuperated closed Brayton cycle

with a variable speed turbine driven compressor and a constant speed turbine

driven generator using S-CO2 as the working fluid. The IST was designed to

demonstrate operational, control and performance characteristics of an S-CO2

Brayton power cycle over a wide range of conditions. The IST design includes a

comprehensive instrumentation and control system to facilitate precise control of

loop operations and to allow detailed evaluation of component and system

performance. A detailed dynamic performance model is being used to predict IST

performance, support test procedure development and to evaluate test results.

An overview of IST testing progress and plans is provided. Testing in the IST was

initiated in 2012. Test operations to date included successful system startup, initial

transition to electrical power generation, increased power operations and transition

to load control testing using independent speed control of the turbo-machinery.

Results of testing completed to date and future testing plans will be summarized.


Supercritical Carbon Dioxide Power Cycle Development Overview

September 10, 2014

KJ Kimball Bechtel Marine Propulsion Corporation

Bechtel Marine Propulsion Corporation Knolls Atomic Power Laboratory Schenectady, NY Bettis Atomic Power Laboratory West Mifflin, PA


BMPC Development Program Overview:

– S-CO2 Brayton Cycle Integrated Systems Test (IST)

• Turbo-machinery (turbine, compressor, bearings, seals)

• Control system (startup, power control)

• Heat exchangers (shell and tube)

• Practical considerations (mass control, instrumentation,

system leakage)

– Compact Heat Exchanger Development

• High pressure, compact, fatigue resistant, affordable

– MW scale development vision

• Based on kW development

• Scale-up issues

• Transition from experimental to demonstration stage


S-CO2 Integrated System Testing



IST Physical Layout

Turbo-Generator

Recuperator

Precooler

Turbo-Compressor (not visible)


IST Turbomachinery Turbo-Generator

Turbo-Compressor

Compressor/Diffuser Turbine

Thrust Bearing


Maximum Power Operation November 2013 – 40kWe

**40 kW on power analyzer


-10

0

10

20

30

40

50

500 1000 1500 2000 2500 3000 3500 4000

Po

we

r (k

W) o

r Ef

fie

cie

ncy

(%)

Time (seconds)

TG Power

TC Power

Brayton Power

Brayton Efficiency

System Up-Power

35000

40000

45000

50000

55000

60000

500 1000 1500 2000 2500 3000 3500 4000

Spe

ed

(rp

m)

Time (seconds)

TC Speed


Compressor Map

Model Prediction for Design Operating Conditions

Test Data


• Initial Conditions: Hot Idle (540°F/37,500 rpm) • TG speed increased • TC speed increased in steps • Compressor recirculation valve decreased in steps • Water flow automatically controlled to maintain compressor inlet T

Turbine-Generator Speed Turbine-Compressor Speed Recirculation Valve Position

Power Increase Transient


Intermediate Hx Recuperator Precooler

Power Increase Transient: Heat Exchanger Heat Duties


IHX Heat Transfer

0

100

200

300

400

500

600

0 100 200 300 400 500 600

Me

asu

red

He

at

Tra

nsf

er

(kW

)

Predicted Heat Transfer (kW)

HTRI w/REFPROP

HTRI w/VMGThermo

Dittus-Boelter

Measured = Predicted


Precooler Heat Transfer


IST with Recompression Cycle Control Features

This loop design shows how recompression control features could be placed in the IST, allowing loop hydraulic control for startup, heatup and low power operation.

Baseline recompressor recirculation


IST Up-Power Maneuver in Recompression Configuration Using end states that have been optimized for adequate surge margin this up-power transient shows good performance, with minimal under/over shoot.

Up-power rates >1%/s would be possible for a well designed recompression loop.


S-CO2 Heat Exchanger Development



Heat Exchanger Testing

Heat Exchanger 1

CO2 PUMP

Heat Exchanger 2

1.5” Tubing with Swagelok fittings

½ or less Tubing with Swagelok fittings

2” to 10” sched 160 Pipe (316 SS)

DP3 2468 psig

T1 Recuperator vessel

DP1

Water heat Source 1

vent

HP-8

P1

HP-9

DP 2

T4

T3

ANSI Flange

Grayloc Flange

1” Tubing with Swagelok fittings

Water heat Source 2

(2) 10x2 Reducer

HP-2

Temp Conn 1

T2

River Water Cooling

(2) 3” graylocx to 2 “ Swagelok adapter

Flow-Meter

(2) Instrumentation Ports

2” Tubing with Swagelok fittings

2” graylocx to 1.5 “ Swagelok adapter

2” graylocx to 1.5 “ Swagelok adapter

Testing Conditions: Heat Input/Rejection 20-90 kWt

Pressure: ≈1,200-1,500 psi Temperature: ≈300-500°F Flow rate: ≈2-3 lbm/second


Recuperator Designs Tested

β=7,000-8,000 m2/m3 β=3,300-4,500 m2/m3


Folded Wavy-Fin Results

50

100

150

200

250

300

350

50 100 150 200 250 300 350

Heat Trnasfer Rate(kW)

Maximum Possible Heat Transfer Rate (kW)

Measured Thermal Performance

1.0 < ṁ <= 1.3

1.3 < ṁ <= 1.7

1.7 < ṁ <= 2.2

2.2 < ṁ <= 2.7

Design Point

ε = 1.0

ε = 0.9

ε = 0.8

(ṁ - lbm/sec)0

1

2

3

4

5

6

7

8

0 0.5 1 1.5 2 2.5 3

Pressure Drop(psid)

Mass Flow Rate (lbm/second)

Measured Hydraulic PerformanceHigh Pressure Side

1.0 < ṁ <= 1.3

1.3 < ṁ <= 1.7

1.7 < ṁ <= 2.2

2.2 < ṁ <= 2.7

Design Point

(ṁ- lbm/sec)

0

1

2

3

4

5

6

7

8

0 0.5 1 1.5 2 2.5 3

Pressure Drop(psid)

Mass Flow Rate (lbm/second)

Measured Hydraulic PerformanceLow Pressure Side

1.0 < ṁ <= 1.3

1.3 < ṁ <= 1.7

1.7 < ṁ <= 2.2

2.2 < ṁ <= 2.7

Design Point

(ṁ - lbm/sec)

Prototype demonstrated thermal-hydraulic performance.


Summary of Progress to Date



S-CO2 Integrated System Testing

• IST demonstrating controllability of a two shaft simple S-CO2 Brayton cycle

• Normal power operation over range of power levels up to ~50 kWe has commenced

• TRACE transient modeling:

– Validation has commenced

– Approaching real time execution

– Demonstrates controllability of re-compression cycle


S-CO2 Heat Exchanger

Development

• IST heat exchangers meeting expectations and validating performance models

• More compact/fatigue resistant heat exchangers being designed, fabricated and tested in dedicated 300kW test facility


MW Scale Development



S-CO2 Power Cycle Development Approach

Fundamental Testing Small Scale System and Component Tests

Large Component Development

Validated Design

Tools

Sandia Closed

Brayton Loops

HX Development & Test

CAPSTONE UNIT

HEATER SECTION

CHILLER SECTION EXPANSION JOINTS

CAPSTONE CONTOLLER

Small System

Test

Large Scale System Test

Plant Concept

Development

Component and System Modeling Development

Power Plant Concept

Development

Concept Development

Operational Test

Corrosion in 825F S-CO2 at 2800 psig

0

0.1

0.2

0.3

0.4

0.5

T-91

410S

S s

hot pee

ned

410S

S

Titaniu

m

Fe52

/ Ni4

8

316S

S s

hot pee

ned

17-7

PH

316S

S

Ni2

00 s

hot p

eene

d

304S

S

304S

S s

hot pee

ned

Allo

y 69

0

Allo

y 60

0

Ni2

00

Ap

pro

xim

ate

Ox

ide

Th

ick

ne

ss

(m

ils

)

1000-1700 hours

500-1000 hours

0-500 hours

Turbomachinery

Performance

Heat Exchanger

Performance

Integrated System Test

Technology Assessment

Fluid Behavior

Safety Implications

Material Behavior


Component Development

Turbomachinery Thermal Coatings Internal cooling

Path to S-CO2 Power Cycle Commercial Implementation Te

chn

olo

gy

Dev

elo

pm

ent

Bearings & Seals

Controls

Engineering Design - Analysis Codes - Component Specifications

Heat Exchangers Chemistry Control

Time

STEP Pilot Plant

~10 MWe FY16

Current

Pre-Commercial

Demo ~30-50 MWe

FY20

BMPC

SNL

Echogen

SunShot

Test loop component development - heater

Applications: Oxy-Fuel /Clean Coal

Concentrated Solar Power High Temperature Nuclear

Geothermal energy Navy Nuclear Propulsion

FY?? Applications: Waste Heat

Industry FY??

Materials Development

MW scale

kW scale

GE

Supercritical Carbon Dioxide Power Cycle Development Overview

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