AggiE-Challenge: Nuclear DesalinationFall 2013

2

Overview

Problem Statement

Economics

Nuclear Reactor Design

Desalination Plant Technologies

The Next Step

3Problem Statement:Design a water desalination plant

Conditions: Energy will be provided by a nuclear plant Plant will utilize thermal vapor-compression desalination (jet

ejector technologies) Plant must be able to supply fresh water to a large city (10 to 12

million people) Questions:

What size, design and type of nuclear reactor will be the most effective?

What is the most efficient scheme of water desalination? i.e. number of jet ejectors, additional collection means, etc.

Is it cost effective to produce electricity in addition to water?

4Desalination PlantNuclear Reactor

Turbine

Jet Ejectors

Brine Fresh WaterSeparator Multi effect

Evaporators

Heat Exchanger

Ocean or other salt water source

Fresh water storage tank

• Steam from Nuclear Reactor• New Steam• Gas/Liquid Mixture • Motive Steam (Superheated)• Entrailed Steam• Salt Water• Product Steam• Fresh Water (Recycle and Product)• Electricity

Power Grid

5

Economics of Water and ElectricityTech/Econ Team

Michael BynumTaufik RidhaGarrett SteigerEmily WilbornJennifer SakowskiJayci BlakeAlexis MussoPreston PhillipsMary Catherine Whitney

6

Location: Los Angeles, California Considering:

Wholesale price of water and electricity Water: $0.0235/ft3 (U.S. Energy Information Administration) Electricity: $39.09/MWh (Olivenhain Municipal Water District)

Necessity for clean water Desperate due to growing population and depletion of Colorado river

Proximity to salt water source The Pacific ocean is huge and very nearby

Opinion towards nuclear energy Not best friends, but cooperating associates out of desperation for

clean water

7

Electricity vs. Water Ratio of water to electricity heavily dependent on local

necessity and potential profits These data are based on a single jet ejector system, with

superheat not including the multi effect evaporator

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 14000

1000

2000

3000

4000

5000

6000

7000

Potential Profits

Total Sales

Water Sales

Electricity Sales

Turbine Discharge Pressure (psia)

Sale

s ($

/h)

Nuclear Reactor Design

Nuclear Team

Jenni BeetgeHanniel Jouvain N. HonangTerrell HughesAyaz MerchantShiv Venkatasetty

9

Outline

Nuclear Technology MotivationSite and Reactor RecommendationSteam GeneratorsPlant Simulation ProgramsPlant IntegrationThe Next Step

10

Nuclear Technology Motivation(Economic Incentives) Fluctuation in natural gas prices

Normal operation of a nuclear power plant is not harmful to the environment No carbon emissions

Power plant life cycles predicted to reach 60+ years

11

Energy Information Administration- U.S. Department of Energy

Economic Incentives

12

Site and Reactor Recommendation Diablo Canyon Nuclear Power

Plant Along Californian coast, near LA 2 Pressurized Water Reactors:

3360 MW(th) each 2240 MW(e) total; ~6720 MW(th) Operational since 1985

Due for license renewal 2024 Modifications provide opportunity for

technology integration Drawback: significant electricity

supplier to CA

Diablo CanyonPlant

LA

13Diablo Canyon nuclear power plant is a PWR from Westinghouse Corporation.

14Nuclear Team Perspective

Steam generator

turbine

condenser

Jet injector

Desalination plant

15

Plant Simulation ProgramsFrom: International Atomic Energy Agency

DE-TOP: Desalination Thermodynamic Optimization Program Limited Functionality

DEEP: Desalination Economic Evaluation Program Results:

Incremental economic estimate for addition of intermediate loop to the system

Comparison of RO, MED Vapor Compression, MSF and base case (electricity only)

16

DEEP Schematic Diagram

17

DEEP, cont.

RO MED

MSF

RO+MED

RO+MSF

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Integration of the nuclear and desalination plants

Problem Feeding water back into the secondary loop requires modification of existing structure, which causes safety and license compatibility issues

SolutionAdditional heat exchanger between the secondary coolant and the motive steam

According to DEEP model, water cost for sample MED VC increases ~$0.06/m3 = $0.22/kgal

LA wholesale price of water is $3.14/kgal

19

Steam generators: Heat exchangers used to convert water into steam from heat produced in a nuclear reactor core.

Advantage: The radioactive water/steam never contacts the turbine or other element in the secondary loop

Steam Generator Analysis

20

Heat exchanger failures in nuclear plants

Denting: Caused by buildup of corrosive material in the space between the tube and the plane

Fatigue cracking: Caused by tube vibration Fretting: Wearing of tubes in their supports due to flow induced vibration Pitting: local breakdown in the protective film on the tube Tube wear: Thinning of the tube caused by contact with support structures

either as the tube vibrate or as feed water entering the vessel

Not accommodating for failures is costly and expensive

22

Include an extra steam generator to accommodate for any upcoming failures in the desalination plant.

Steam Generator Recommendation

23

24

Desalination Plant TechnologiesTech/Econ Team

Michael BynumTaufik RidhaGarrett SteigerEmily WilbornJennifer SakowskiJayci BlakeAlexis MussoPreston PhillipsMary Catherine Whitney

25

Outline

TurbineJet EjectorsSuperheatMulti Stage Jet EjectorsMulti Effect EvaporatorSummaryFuture Work

26High Pressure Turbine Use high pressure turbine to

take some of the energy from the steam to produce electricity

Supplement the desalination plant and the nuclear reactor

Sell back into the grid Depending on location selling

electricity may be more profitable than water

Makes plant more versatile

http://telegraphgh.com/uploaded/pictures/engine_steam_turbine.gif

27Determining Power Production and Desalination Capacity Goal: Determine the amount of water that can be desalinated

and the amount of power that can be produced to evaluate the effect of different operating conditions

Process for a single stage: Specify:

Mass flow rate of working steam Steam turbine inlet conditions (Sat. steam at ~1250 psia) Steam Turbine Discharge Pressure (vary) Steam turbine efficiency (80%)

Determine the power production

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Power Production

whereη = turbine efficiency

Plus 1 mass balance to determine the vapor fraction

29Determining Power Production and Desalination CapacityGoal: Determine the amount of water that can be desalinated

and the amount of power that can be produced to evaluate the effect of different operating conditions

Process for a single stage: Specify: Mass flow rate of working steam Steam turbine inlet conditions (Sat. steam at ~1250 psia) Steam Turbine Discharge Pressure (vary) Steam turbine efficiency (80%)

Determine the power production Determine the desalination capacity Jet Ejector calculations – mass flow ratio

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Jet Ejectors Low maintenance devices, requiring no

moving parts, that can be easily replaced or repaired

Uses a fast moving “motive” stream of steam to evaporate fresh water out of a supply of salt water or brine

Driven by an enthalpy difference between the inlet and outlet nozzle

http://www.primetechrkg.com/images/steam_jet_ejector.jpg

Motive Stream

Entrailed Stream Product Stream

Brine Fresh Water

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Mass Flow Ratio

whereη = nozzle efficiencyΔH = Enthalpy drop across the nozzle

where = Dimensionless Group

32

Mass Flow Ratio

33Power vs. Desalination Capacity (Single Stage)

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 14000.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

0.0

500.0

1000.0

1500.0

2000.0

2500.0

3000.0

3500.0

Turbine Work and Distillate Flow Rate as a Function of Discharge Pressure

WT MW

Distil-late Rate (Mlbm/h)

Turbine Discharge Pressure (psia)

Turb

ine

Wor

k (M

W)

Dist

illat

e Ra

te (M

lbm

/h)

34

Superheat Steam from the turbine is superheated before being sent

through the jet ejector Adding 50 degrees of superheat to the motive steam

increases the mass flow rate on average 50%

0 200 400 600 800 1000 12000.05

0.06

0.07

0.08

0.0900000000000001

0.1

0.11

0.12

0.13

0.14

0.15

0.16

0.17

0.18 Superheat vs. No SuperheatNo Superheat+50 degrees F Superheat

Motive Steam Pressure (psia)

Mas

s Fl

ow R

atio

35Multi Stage Jet Ejectors Jet ejector system where multiple jet ejectors are used in a

series of stages to gradually increase the concentration of the waste brine

For a ten stage jet ejector, efficiency (distillate mass per amount of motive steam) increased by an average 15% depending on the turbine discharge pressure

Assuming each jet ejector is the same size

Turbine discharge pressure

(psia)

Distillate mass/motive

steam (single)

Distillate mass/motive steam (multi)

Distillate rate (million lbm/hour) (single)

Distillate rate (million lbm/hour) (multi)

Percent increase

300 5.48 6.24 2467 2810 14.03

400 5.36 6.37 2451 2910 18.73

500 5.60 6.42 2595 2580 14.84

600 5.61 6.39 2636 3000 13.81

Average 5.5125 6.355 2537.25 2825 15.3525

36Multi Effect Evaporator Part of the steam from the jet ejector exhaust is diverted to a

multi effect evaporator to squeeze the last bit of energy out of the motive steam and produce more fresh water

Multi effect evaporator example:

Fresh water Brine Fresh

water BrineFresh water Brine

From product stream of jet ejector

Salt water Source Fresh

water Storage

Enter:5 lbm steam at 120 psia

Effect 1: 120 psia Effect 2: 100 psia Effect n: 14.7 psia

5 lbm fresh water produced per effect

5 lbm water vapor produced per effect

Total fresh water produced = 5+5+(5*n) lbm

37

Multi Effect Evaporator Example calculations for a ten

stage multi effect evaporator Multi effect evaporators allow for the most economical use of the remaining energy from the jet ejector product steam 120 psia: 17920 Btu/(h*ft2*F)

Number of Effects

Final Pressure Final U

  psia Btu/(h*ft2*F)10 91.65 1073120 67.6 602230 49.8 336340 36.5 1866

38Summary

39

The Next Step: Spring 2014 Simulate the plant or segments of the plant for technical and

economic feasibility Using ASPEN, MATLAB, DEEP

Co-generation decision: Pending Future Research…

40Future Research (1) Find the most efficient number of

jet ejector stages Calculated by the increase in

distillate mass per amount motive steam

Find the most efficient turbine discharge pressure Based on the most efficient number

of stages Consider producing electricity to

maximize profits Calculate the most efficient jet

ejector sizes and the sizes for each stage Inlet and outlet nozzle diameter,

length May be different for each stage

http://images.engineeringnet.eu/RSS/feeds_P-mag/images/steamjet2.jpg

41Future Research (2) Interpolation from the existing dimensionless group is only valid if the

operating pressure is at atmospheric pressure. If operating pressure > atmospheric, the deviation must be accounted for

before interpolation.

(Momentum Ratio)arb=(Momentum Ratio)ref +(Momentum Ratio)ref

·(Momentum Ratio)dev

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Future Research (3) Calculate the most cost efficient number and size of effects

Consider heat exchanger size, material, cost Each effect may be different

Calculate cost of the entire multi effect system Is it a cost efficient system?

http://www.redaspa.com/wp-content/uploads/2013/04/UP_10-11-11_8lkPe8.jpg

43Future Research (4) Research different locations to maximize profits In depth analysis of plant costs and profits including:

Cost of nuclear reactor, turbine, jet ejectors, multi effect evaporators and other associated plant costs

Full analysis of profits, how long it will take to recover from startup costs etc.

http://deathandtaxesmag.wpengine.netdna-cdn.com/wp-content/uploads/2011/11/Stacks-of-money-pictures-3.jpg

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