"Wireless applications in "Wireless applications in industry: the aluminum industry industry: the aluminum industry

as a prototype"as a prototype"

Prof. James W. EvansProf. James W. EvansDept. of Materials Science and Engineering, UCBDept. of Materials Science and Engineering, UCB

Collaborators: Mike Schneider, Prof. Paul WrightCollaborators: Mike Schneider, Prof. Paul Wright

(Dan Steingart, Andrew Redfern & Nathan Ota)(Dan Steingart, Andrew Redfern & Nathan Ota)

Support from UCEI & HoneywellSupport from UCEI & Honeywell

OutlineOutline

1.1. Introduction – energy consumption Introduction – energy consumption by industry, the production of by industry, the production of aluminum.aluminum.

2.2. Why wireless instrumentation?Why wireless instrumentation?

3.3. Overview of wireless sensing Overview of wireless sensing devicesdevices

4.4. Previous campaigns Previous campaigns

5.5. Campaign in April, 2005 at EastalcoCampaign in April, 2005 at Eastalco

6.6. Conclusion from work so farConclusion from work so far

7.7. Other industries?Other industries?

From Energy Information From Energy Information AdministrationAdministration2002 statistics2002 statistics

US production of energy (all US production of energy (all uses): 70.8 quadsuses): 70.8 quads

US consumption of energy for US consumption of energy for manufacturing:manufacturing:22.7 quads of which electricity is 22.7 quads of which electricity is 832 trillion kWh832 trillion kWh

Electrical energy consumption by Electrical energy consumption by primary aluminum industry in US: primary aluminum industry in US: 56.7 trillion kWh56.7 trillion kWh

Aluminum – the good Aluminum – the good newsnews

Use of aluminum in vehicles, rather Use of aluminum in vehicles, rather than steel, reduces vehicle weight than steel, reduces vehicle weight significantly = improved gas significantly = improved gas mileage = lower COmileage = lower CO22 emissions. emissions.

Aluminum beverage can recycling is Aluminum beverage can recycling is an environmental success story.an environmental success story.

Use of aluminum in construction, Use of aluminum in construction, rather than wood, conserves forests. rather than wood, conserves forests.

Aluminum – the bad newsAluminum – the bad news

Primary production of aluminum Primary production of aluminum consumes large amounts of electrical consumes large amounts of electrical energy – more than the electricity energy – more than the electricity consumed by the whole of France.consumed by the whole of France.

Primary production of aluminum Primary production of aluminum generates large amounts of greenhouse generates large amounts of greenhouse gasses. E.g. in 1997 110 million tonnes gasses. E.g. in 1997 110 million tonnes of COof CO22 equivalents, of which 50 million equivalents, of which 50 million tons of COtons of CO22 equivalents were PFCs. equivalents were PFCs.

Aluminum industryAluminum industry

Major primary producers:Major primary producers:

USUS

CanadaCanada

RussiaRussia

ChinaChina

NorwayNorway

23 smelters in US a few years ago, 23 smelters in US a few years ago, now 19now 19

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

Pri

mar

y al

umin

um p

rodu

ctio

n (t

hous

ands

of m

etri

c to

ns)

1998

1999

2000

2001

2002

2003

2004

Energy consumption per kg of Al Energy consumption per kg of Al over last centuryover last century

Hall (- Héroult) cellsHall (- Héroult) cells

About size of a shipping container.About size of a shipping container. Contain molten fluoride electrolyte at Contain molten fluoride electrolyte at

950-960950-96000C.C. Current (100-500kA) passes in through Current (100-500kA) passes in through

carbon “anodes”, flows through molten carbon “anodes”, flows through molten salt to top surface of aluminum pool then salt to top surface of aluminum pool then into “cathode” at bottom of cell, hence to into “cathode” at bottom of cell, hence to next cell.next cell.

Only instrumentation is voltage Only instrumentation is voltage measurement.measurement.

One source of fluoride One source of fluoride emissionsemissions

Contact between air and molten Contact between air and molten fluoride produces fluoride emissions.fluoride produces fluoride emissions.

Contact minimized by:Contact minimized by: Maintaining frozen “crust” on top of saltMaintaining frozen “crust” on top of salt Keeping panels in place to minimize air Keeping panels in place to minimize air

inflow into duct system and fugitive inflow into duct system and fugitive emissions from cell.emissions from cell.

These made difficult by need to These made difficult by need to replace/adjust anodesreplace/adjust anodes

Lack of InstrumentationLack of Instrumentation OnlyOnly continuous measurement is of cell voltage continuous measurement is of cell voltage and currentand current

Intermittent measurements of mass of siphoned Al, and Intermittent measurements of mass of siphoned Al, and bath temperaturebath temperatureWhat causes this lack of What causes this lack of

instrumentation?instrumentation? Safety concerns with wires running around Safety concerns with wires running around potlinespotlines Cost of running wiresCost of running wires Possible interference with existing hardware Possible interference with existing hardware Lack of a reliable, maintenance free, continuous Lack of a reliable, maintenance free, continuous power sources for sensors power sources for sensors Solution: Solution: Energy-Scavenging Wireless SensorsEnergy-Scavenging Wireless Sensors

Wireless Sensing TechnologyWireless Sensing Technology

Mote Processor-Radios (MPRs): Mica2 from Mote Processor-Radios (MPRs): Mica2 from Crossbow Technology, Inc., model # MPR400:Crossbow Technology, Inc., model # MPR400:

3rd Generation, tiny, wireless smart sensors3rd Generation, tiny, wireless smart sensors 8 channel 10 bit ADC converter8 channel 10 bit ADC converter FM tunable radio (set manually to FM tunable radio (set manually to 916 MHz) 916 MHz) Transmit up to 500 feet outdoors Transmit up to 500 feet outdoors with a 1/2 wave dipole antennawith a 1/2 wave dipole antenna Draws maximum 26 mA (@ 3V Draws maximum 26 mA (@ 3V ~80mW) in full power mode ~80mW) in full power mode

(8 (8 A in sleep mode)A in sleep mode)

Objectives of Eastalco Objectives of Eastalco campaignscampaigns

1.1. Test concept of wireless cell monitoring (would Test concept of wireless cell monitoring (would strong magnetic fields interfere with wireless strong magnetic fields interfere with wireless devices?).devices?).

2.2. Monitor conditions in duct from a cell (pressure or Monitor conditions in duct from a cell (pressure or temperature) to see if cell crust intact and cover temperature) to see if cell crust intact and cover panels in place (so as to minimize emissions). panels in place (so as to minimize emissions).

3.3. Measure heat flux from shell of a cell (perhaps a Measure heat flux from shell of a cell (perhaps a diagnostic for sidewall condition).diagnostic for sidewall condition).

4.4. Test notion of powering wireless devices by Test notion of powering wireless devices by “energy scavenging”, rather than batteries.“energy scavenging”, rather than batteries.

Campaigns at EastalcoCampaigns at Eastalco

Early 2004:Early 2004: Duct pressure measurement successful but uselessDuct pressure measurement successful but useless Motes undisturbed by magnetic field and Motes undisturbed by magnetic field and

communicate properly (about 100 ft)communicate properly (about 100 ft) Late 2004:Late 2004:

Motes self powered from thermoelectric Motes self powered from thermoelectric generators (TEGs)generators (TEGs)

Development of DC-DC power conditioning for Development of DC-DC power conditioning for TEGsTEGs

Successful duct temperature measurement Successful duct temperature measurement Magnetically attached motes Magnetically attached motes

Mechanical Design #1 – Duct Mechanical Design #1 – Duct Insert TEG HousingInsert TEG Housing

Thermistor Housing

7” extension into Exhaust Duct

Cutaway view of Heat Sink

Single Tellurex TEG

Mica 2 Mote

DC/DC Converter

Hot Plate V2 (designed for specific TEG)

1”

Complete AssemblyComplete AssemblyHot side

machined to the

curvature of the duct

Heat Sink(cold side)

7” extension intoduct

Thermistor

Mica 2 Mote

DC/DC Converter

Cross-Cut Heat Sink

Mechanical Design #2 - Mechanical Design #2 - Magnetically Attachable TEG Magnetically Attachable TEG

Housing Housing

Use same electronics in previous Use same electronics in previous designdesign Can be placed on any flat Can be placed on any flat ferromagnetic material w/ Temp < ferromagnetic material w/ Temp < 225225oo C C

Samarium-Cobaltmagnets

TEG

Cross-CutHeat sink

Experimental results – Networking Experimental results – Networking CapabilitiesCapabilities

Sample TrialSample Trial

0

100

200

300

400

500

600

Suce

ssfu

l que

ries

1 3 6 7 8 9 10 11 12 13 14

Node ID

721 possible Queries (sampled at 1/ 12 Hz for ~3.5 hours)

Thermoelectrically powered 3 /

Node 1 removed

Node 3 added

Experimental results – Experimental results – NetworkingNetworking

Base Station

15’

20’

Thermoelectrically powered nodes

ID = 7

6

9

10

1

12

3 11

13 14

= Cell

Legend:

= Mote

*Note: All nodes were battery powered unless otherwise noted

8

Last two campaigns at Eastalco Last two campaigns at Eastalco (March/April, 2005)(March/April, 2005)

Eleven motes/laptop at Eastalco for Eleven motes/laptop at Eastalco for approx three weeksapprox three weeks

Four motes powered from Four motes powered from thermoelectric generators (TEGs)thermoelectric generators (TEGs)

Measurement of heat flux from shell Measurement of heat flux from shell & gas temperature in duct& gas temperature in duct

Data transferred by internet to ATC Data transferred by internet to ATC and UCBand UCB

April 2005 at Eastalco; mote April 2005 at Eastalco; mote layoutlayout

Last campaign – representative Last campaign – representative resultsresults

Heat Flux and Temperature vs. Time on 4/ 17/ 05 for Cell B127

80

90

100

110

120

130

140

150

160

0:00 2:24 4:48 7:12 9:36 12:00 14:24 16:48 19:12 21:36 0:00

Time

Tem

pera

ture

(C)

6000.000

6500.000

7000.000

7500.000

8000.000

8500.000

9000.000

9500.000

Temperature .Heat Flux, W/sq .m

Anode change?

Pot tending?

Duct temperature and shell heat flux, Duct temperature and shell heat flux, “day 5”“day 5”

Nine days of dataNine days of data

Sun Mon

Conclusions from past Conclusions from past workwork

Wireless instrumentation of pots has been Wireless instrumentation of pots has been demonstrated (for a period of about two weeks)demonstrated (for a period of about two weeks)

The wireless devices (sensing motes and relay The wireless devices (sensing motes and relay motes) can be self powered using TEGsmotes) can be self powered using TEGs

Gas temperatures in pot ducts carry signatures Gas temperatures in pot ducts carry signatures of correct (or incorrect) pot operationof correct (or incorrect) pot operation

Heat fluxes from pots are at very far from Heat fluxes from pots are at very far from steady state – show diurnal variation probably steady state – show diurnal variation probably due to variation of potroom temperature – due to variation of potroom temperature – statistical/modeling treatment needed for statistical/modeling treatment needed for reliable value.reliable value.

Applications of wireless Applications of wireless technologytechnology

to Hall cells – why a good to Hall cells – why a good prototype studyprototype study

Hall cells ideal test case because of:Hall cells ideal test case because of: Limited instrumentation at presentLimited instrumentation at present Significant energy consumption (and energy Significant energy consumption (and energy

efficiency only approx. 45%)efficiency only approx. 45%) Safety issues in wired instrumentationSafety issues in wired instrumentation Large number of cells per plant (few hundred in Large number of cells per plant (few hundred in

a “potline”) and large number of plantsa “potline”) and large number of plants Opportunities for energy scavenging to power Opportunities for energy scavenging to power

sensors and electronicssensors and electronics

What’s in the future?What’s in the future? Complete instrumentation of an aluminum Complete instrumentation of an aluminum

smelter (not just duct temperatures). smelter (not just duct temperatures). Instrumentation of similar plants (copper, Instrumentation of similar plants (copper,

zinc, magnesium, chlor/alkali ….)zinc, magnesium, chlor/alkali ….) Application to other industries Application to other industries

(papermaking, weaving, (papermaking, weaving, petrochemicals…..). Best when:petrochemicals…..). Best when: Many “small” production unitsMany “small” production units Instrumentation presently lacking but valuableInstrumentation presently lacking but valuable Cost/safety inhibit wired sensorsCost/safety inhibit wired sensors Opportunity for energy scavengingOpportunity for energy scavenging