O i R ki C l (ORC)Edmund Wong, Snr Vice President, NatSteel holdings Pte Ltd

Organic Rankine Cycle (ORC)Waste Heat Recovery SystemWaste Heat Recovery Systemat Rolling Mill Reheating Furnace

2013 National Energy Efficiency ConferenceOct 9-10 2013 | Max Atria Singapore EXPO

Team members:Ng Kek LoonChew Wei KangT E JiOct 9 10 2013 | Max Atria, Singapore EXPO Tan Eu JinPhua Wung KiongThangavel Yogesh

Agenda• Introduction – NSH• Operations – energy intensive• Steel Mill and Waste Heat• Electricity Cost and Trend• Waste Heat Recovery – basic concept• Feasibility study

• Potential cost savings• ROI

• The ORC Plant• Project Milestones• Results

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Introduction of NatSteel Holdings. Singapore • NatSteel operates a steelmaking and rolling mill (capacity of 750K TPY), and a

downstream businesses of cut & bend bars, welded mesh and prefabricated cages (500K TPY) at 22 Tanjong Kling Road Jurongcages (500K TPY) at 22 Tanjong Kling Road, Jurong.

• Employs about 1800 people in its Singapore Plant.

P t f T t St l G• Part of Tata Steel Group.

Facilities:• One 80 tonne DC electric arc finger• One 80-tonne DC electric arc finger

shaft furnace • One 80-tonne ladle furnace• One high-speed 4-strand• One high-speed 4-strand

continuous casting machine• High speed rolling mill to produce a

full range of rebars round bars andfull range of rebars, round bars and wire rods

• The latest cut-and-bend machines for accurate fabrication of rebars.o accu a e ab ca o o eba s

• State-of-the-art machines for production of cold rolled wires, stretched wires and welded wire mesh.

3

Operations – Energy Intensive

Rolling MillMeltshop

Molten steel Billets Wire rod

4

Steel Industry and Waste GasNatSteel initiated its Climate Change initiative in FY11 through one of its PerfEx committees Clean Green andNatSteel initiated its Climate Change initiative in FY11 through one of its PerfEx committees – Clean, Green andSafe Committee. Key strategy was to optimize usage of energy, material resources and reduce its carbon footprint in achieving environmental sustainability (and possibly profitability) for a less carbon intensive economy.

5

Electricity Cost and Trends2012Electricity Bill -2012

Annual Electrical Power Consumption

Areas KWH USD

Meltshop 290,000,000 44,615,385

• Average electricity rate: S$0.20/Kwh (USD 0.15)

Rolling Mill 62,000,000 9,538,462

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Electricity Cost and TrendsS 2000 2011Singapore Electricity Rate: 2000-2011 (USD/Kwh)

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Waste Heat Recovery – Basic Concept Big Ticket

Released to th i W t

Recover part of the Waste Heat’s Th l E t d ithe air - Waste

HeatThermal Energy to drive• Generator (electricity)• Compressor (compressed air)p ( p )• Steam Turbine (Steam)

Off Gas

Released to the air -

Waste Heat(High Temp)

600 °C

Off Gas(Low Temp)

150 °C

Process / Equipment releases hot gas into the atmosphere (RHF)

150 C

Process / Equipment releases hot gas into the atmosphere (RHF)8

Feasibility Study (2011)

• We engaged GCT, a metallurgical Process Specialist from USA to conduct a feasibility study to assess the potential, scope and magnitude of waste heat recovery opportunity in our Singapore plantrecovery opportunity in our Singapore plant.

• ORC (Organic Rankine Cycle) Waste Heat Recovery System was deemed to be the most suitable technology for our off gas condition (temperature, volume, flow rate, thermal dynamic).y )

• The challenge: ORC is a mature technology and is widely used in Bio mass• The challenge: ORC is a mature technology and is widely used in Bio-mass and Bio-gas industries. But we were not able to find any application of the ORC system in the steel mill industry.

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Potential Cost SavingsReheat Furnace Heat Recovery System ROI AnalysisExit Temperature =135 ⁰C ( Ref: GCT, Payken email 12/07/2011)p ( f , y / / )Hot Charge Condition Flow rate of gas at inlet of heat exchanger (371⁰C) Nm3/hr 24,100 -Enthalpy of gas at inlet W/Nm3/hr 145.88 -Heat content of gas at inlet kW 3,516 -gEnthalpy of gas at outlet of heat exchanger (135⁰C) W/Nm3/hr 45.70 -Heat-content of gas at outlet kW 1,101 -Heat recovered from gas kW 2,414 -Gross power generation@20% conversion efficiency kW 483 -p g @ yNet power generation@60Kw parasitic load kW 423 -Cold Charge ConditionFlow rate of gas at inlet of heat exchanger (338⁰C) Nm3/hr 47,300 -Enthalpy of gas at inlet W/Nm3/hr 128.60 -Heat content of gas at inlet kW 6,083 -Enthalpy of gas at outlet of heat exchanger (135⁰C) W/Nm3/hr 44.85 -Heat content of gas at outlet kW 2,121 -Heat recovered from gas kW 3,961 -Gross power generation@20% conversion efficiency kW 792 -Net power generation@100kw parasitic load kW 692 -% utilization % 91.00% 80.00%Annual Operating hours Hrs 8,000 7,008 Hot Charge operating hours hours 6,400 5,606 Cold Charge operating hours hours 1,600 1,402 Net Annual power savings kWh 3,813,993 3,341,165 Net Annual power generation kW 477 477 Simple ROICapital Cost (SGD)  USD 3,700,000 3,700,001 Net Annual Power Savings U$0.162/kWh 617,867 541,269

U$0.194/kWh 739,915 648,186

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ROI U$0.162/kWh 16.70% 14.63%U$0.194/kWh 20.00% 17.52%

Return of Investment

• Project Schedule:12-15 monthsProject Cost USD 3.70 M

• We applied for Energy Funding from NEA-National Environmental

Net Annualized Power Generation  Kw 480

Net Annualized Power SavingsAgency of Singapore:USD 1.5M (SGD 2.0M)

Net Annualized Power Savings (80%‐90% mill utilization)

MWH 3,300 ‐ 3,800

CO2 Emission Reduction Tons CO2 1,700 ‐ 2,000, ,

Net Annualized savings from Power Generation USD 650k ‐ 750k

Simple ROI Years 5.0 ‐ 5.7 

(*) www.nef.org.uk/greencompany/co2calculator.htm

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The ORC Plant

Direct Close-Loop Organic Rankine CycleW H R SReheat

FurnaceCombustion

Waste Heat Recovery System At Rolling Mill Reheat Furnace

Generator / Compressor

Combustion Air Out(400°C)

Recuperator

Waste heat(335-370°C)Waste heat

Cooling Tower

Condenser

( )(680°C)

Propane gas (310°C)

Combustion Air In (29°C)

Heat ExchangerExpander

PumpPropane liquid (40°C)

I.D. Fan

Stack / ChimneyPropane storage tankPumpWaste heat

(120°C-150°C)

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Stack / Chimney (120 C 150 C)

The ORC PlantContinue

Description

Continue…

p

We have selected Pratt & Whitney-Turboden ORC plant for our application. The ORC plant is integrated into the process flow of our reheating furnace at our rolling mill to recover waste heat from off gas which would otherwise be released to the atmosphere.

The plant is a Direct Coupling Close Loop System. The working fluid is vaporized, expanded in the turbine, condensed in a water cooled condenser and then pumped back to the heat exchanger/evaporator. The vaporization includes p p g p pa first pre-heating and a following vaporization

The heat in the off gas from the reheating furnace (about 400 C) is captured via a heat exchanger in the ORC plant. The working fluid is a organic fluid - Power 2 (Dow Corning R200), chemical name Hexamethyldisiloxane. It has a high molecular weight which makes it suitable for high efficiency low thermal power g g y pand low temperatures application. The off gas’s temperature is brought down to about 130-150 C before being released to the atmosphere through the stack.

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The ORC PlantContinueThe heated up working fluid changes into gaseous state and expanded in a turbo-expander directly connected to an Induction ( asynchronous) Generator t d l t i it Th d d th t d d i th t bi i b t

Continue…

to produce electricity. The produced vapour that expanded in the turbine is about 9 bar abs and 200 C. The vapour exists the turbine at about 0.16 bars abs. i.e. it is under vacuum.

Safety - Flange connections were used in the plant. Welding connections are not used as they are possible leaking points. Gas leak detectors are installed at

d th fl A di h i ll th t b di h d t tharound the flanges. A discharge pipes allows the vapour to be discharged to the air in an emergency case.

All the possible leaking points are flushed via a system that aspirates the airAll the possible leaking points are flushed via a system that aspirates the air around the possible leaking points in order to assure a non explosive atmosphere in all the point. In case of leak, the working fluid content is below LEL (L E l i Li it) i b l th fl bilit th h ld Th t illLEL (Lower Explosive Limit) i.e. below the flammability threshold. The system will stop the plant when concentration of organic fluid higher than 10% of the LEL is detected.

A housing was built around ORC plant with force ventilation. This keeps the room temperature at below 40C and dilute any working fluid concentration in the

di i h f l ksurrounding area in the event of leakage. 14

Turboden-7 Schematic Diagram

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ORC System on Skid

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Heat Exchanger

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ORC System Installed Next to RHF

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Project Milestones…

• Mid 2011: Feasibility Studies• Aug 2011: Agreement with GCT-Ateag g• Mar 2013: Complete installation and first unit of electricity generated.• Apr-May 2013: Commissioning and Synchronisation with Rolling Mill p y g y g

production• May 2013: Shutdown for Plant Upgrading*• Oct 2013: Resumption of ORC system, fine-tuning for optimisation

*Plant Upgrading ShutdownWe took on a planned shutdown to implement a major upgrade to the rolling mill’s productivity for small diameters sizes, to increase output volume.

Next the results thus far19

Next…the results thus far…

Electrical Power Generated by ORC SystemDaily & Cumulative (all results’ 3rd party verification done by PE)Daily & Cumulative (all results 3 party verification done by PE)

109,39010,000

SCADA - GrossEnergy Generated (kWh)

8,539

82,354

105,152100,000

7,500

h)

Nett Energy Generated (kWh)

LV3 Meter Gross Generated (kWh)

Cumulative Net Energy7,202

82,354

75,000

kWh)

Scal

e (k

Wh Cumulative Net Energy

Generated (kWh)

SCADA Cumulative Gross Energy Generated (kW)

LV3 Meter Gross Generated C m lati e

50,000

5,000

ve S

cale

(k

Gen

erat

ion Cumulative

25,0002,500

Cum

ulat

iv

Dai

ly G

00

- First testing phase was synchronisation of the ORC system with the rolling mill’s dynamic production conditions. There were gaps in the consistency of electricity generated.

00

g p y y g- The next phase (starting from Oct’13) will be on fine-tuning to maximise the energy generated; to

achieve designed system thermal efficiency of ~20%20

Electrical Power Generated by ORC SystemAgainst MBM’s operating conditions and output (all results’ 3rd partyAgainst MBM s operating conditions and output (all results 3 party verification done by PE)

100%120,00010,000

8,590 kWh100,000

8,000

9,000

Wh)m

t)

Cold Charge %

LV3 Meter Gross Generated (kWh)

66%73%

56%60%

6,750 kWh 80,000

6,000

7,000

nera

ted

(kW

on V

olum

e (m

Total Volume Produced

LV3 Meter Gross Generated

44%

56%

3 970 kWh

4,900 kWh 60,0005,000

6,000

ectr

icity

Gen

nd P

rodu

ctio Generated

Cumulative

44%

24%27%

31%

3,970 kWh

2 139 t

40,0003,000

4,000

mul

ativ

e El

e

wer

(kW

h) a

n

8.3%

13.7%1,586 mt

2,139 mt

20,000

1,000

2,000

Cu

Pow

00

1,000

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More electricity produced with higher cold charge; consistent with initial project objectives No clear relation to MBM’s output volume (in metric tonnes) Duration of ORC in operation in-sync with MBM’s operation time.

Electrical Power Generated by ORC SystemAgainst product sizes. (all results’ 3rd party verification done by PE)Against product sizes. (all results 3 party verification done by PE)

2,299100.00

90

1002,480 Average of Gross Energy Generated (kWh)Average of Cold Charge

A f N t E

1,86874.5078.60

1,884

70

801,980

h)

Average of Net Energy Generated (kWh)

1,574 1,567 1,703 1,516 1,47662.00

50 25

1,518

1,30850

60

70

1,480

arge

%

raet

ed (k

W

984

823909

48.97 49.00

36.20 34.00

50.25

807

1,184 1,256 1,171 1,12940

50

980 Col

d C

h

ergy

Gen

er

664

322 18.13

26.6822.34

393

807

626 668

20

30

480

Ene

29 1310 0

6.0012.00

7.1017154 0 -13 0

10

-20

Achieved consistent good generation for larger bar sizes (28, 32 & 40)mm and wirerod 10amm. Further fine-tuning required for the other product sizes to optimise ORC system for maximum power

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Further fine-tuning required for the other product sizes to optimise ORC system for maximum power generation with given fluctuations in reheating furnace operating parameters owing to different sizes.

Thank You

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