Waste Heat Recovery & Renewable Energy Projects in Aluminium production

Opportunities & Challenges

Debasish Ghosh Hindalco Industries Limited debasish.g@adityabirla.com 16.12.16

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Contents

• Waste Heat sources in Aluminium Production

• Waste Heat Recovery - Opportunities & Challenges

• Renewable Energy - Opportunities & Challenges

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Power Plant Co-generation

WH WH

WH

WH

Aluminium Production & Waste Heat

WH – Waste Heat

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Smelter

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CFD Model in Smelter

Relation – Duct Flow & Energy Consumption Duct flow : If can be decreased from 5900 to 4000 [Nm3/h] Duct temp : 20.5°C higher (168°C).

Constant : Current (180.7 kA), ledge thickness and shell heat flow Possibility : ACD squeeze Energy : 14.090 to 13.401 [kWh/kg Al]

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Smelter - Other Cell Material Flow Energy loss

Around 0.35 [kWh/ kg Al] (2%-3%) of cell energy is consumed by parallel materials heat up and reactions

reduce time spent per anode change, improve the cover practices to

generate less sludge, reduce gross and net carbon consumptions.

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Smelter – Waste Heat Recovery

Typical Gas duct in Smelter

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Smelter – Waste Heat Recovery

Off Gas temp : 150 – 200 deg C Hydro smelters are utilizing the recovered heat in space and district heating schemes. heat exchangers (HXs) have been set up downstream of the dry scrubbers,

With HXs upstream of dry scrubber Advantages Better heat availability Lower size of HXs Potential for reducing the exhaust fan power consumption Extending the filter-bag life in the dry scrubber (temp below 135°C)

Concern fouling and corrosion of heat exchange Utlisation of the heat energy Power Generation through ORC ? Other Area : Anode Baking Furnace

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Waste Heat Recovery– An example Belgaum Refinery • In-house fabrication of the air pre-heater at minimum cost • Flue gas temp brought down to 145 deg C and savings 9.3 MT Oe /month

FLUE GAS TO APH

FD FAN

BOILER & ECON (INTEGRAL)

COLD AIR IN

BY-PASS DAMPER

TO STACK

NEW AIR PRE-HEATER

Status : Implemented

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Waste Heat Recovery - Refinery

Waste Heat Recovery in KILN > Hydrate Drying(7 to 8 % moisture) /Preheating > 9000m3/Hr flue gas at 200-210 Deg C > Investment Rs 72.0 Lakhs > Savings : fuel oil 10 Kg/T

Status : Not yet implemented

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Waste Heat Recovery - Remelting

A typical Example Heat Source : Remelting Furnace Flue Gas Utilisation : Ingot Preheating Mode : Initial heating by Waste Heat Final Heating by Electricity Savings : 70 kWh/t Drawback : Cy time increase from 12 to 17 Hrs

1) Recuperators 2) Regenerative Burners 3) Additional potential

Status : Implemented but not in use now due to cycle time/productivity concern

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Waste Heat Recovery - Aluminium Production

Sources Smelter Duct Gas Anode Baking Furnace Refinery Calciner Remelting Furnace

Utlisation Hot water application Air preheating Preheating of Charge/Raw material Refrigeration/Chillers through VAM Power Generation through ORC ?

Challenges High grade heat – available in batches Low grade heat – Technology & Economics Fouling of Heat Exchanagers

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Renewable Energy

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Sun Pipe light Installation at Belur FRP Plant

Machine Shop Shop floor

In its simplest form :

Status : Implemented

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Solar Power

First MW scale Solar project for Hindalco

Alupuram, Kerala Solar 1 MW - commissioned 31.03.16 Seasonal Tilt, synchronised at 11 kV Consumption : 100% Captive Monthly PLF : upto 18% Performance Ration (PR) : @ 78% Daily Generation : 5,800 kWh (max) Monthly Generation : 1,50,000 KWh (max)

Status : Implemented

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30 MW Solar

Substitute part thermal power by solar in Smelter Plant with CPP

Land requirement @ 140 – 150 Acre

Cannot synchronise at 11 kV & 33 kV for plant reliability/stability

To synchronise at 220 kV

Some loss of PLF in CPP resulting in PHR increase by 2 kcal/kWh (BEE Method : Design efficiency curve validated by operating data)

Need to regulate CPP generation with hour of the day/sunshine

Requires Operational control to restrict both Import/Export of Power

Status : In progress

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Renewable Power for Captive consumption

Infirm in nature / Alternate source also required

Some efficiency loss in existing Thermal Power Plant

Available location may not be the ideal

States like Odisha do not have wind potential

Country Green corridor not yet ready

Interstate Renewable power transfer not yet established

Banking of power not allowed in most states

Govt. Policy & Regulations are constantly evolving

Concerns

Favourable Falling Prices of Solar Panels/Projects

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Aluminium sector (12 units with CPP totalling approx. 6660 MW)

Unique sector with high ratio of electricity to thermal energy

Large power plants to meets its own electricity need.

High renewable % high capacity/ratio of Renewable energy in overall mix

unfavourable operational/reliability/efficiency/feasibility

Increases cost of production substantially

LT Renewable Trajectory set by MoP will need 3400 MW of RE Power for Al sector

Appears technically difficult & detrimental

There are constraints, we need to progress to the maximum feasible

From BEE PAT consultation document

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Thank You