NIPSCOMichigan City Generating Station

Michigan City Generating Station•Located in Michigan City, IN (50 Miles SE of Chicago) •Owned by NIPSCO a division of Nisource Inc.•Number of employees 90•Capacity ~500 MWg. In service 1974p y g•G.E. Dense Pack Steam Turbine G2 (2008)•Steam Generator B&W (UP76) Cyclone fired (10)O i i ll d i d f Bit i C t d t PRB•Originally designed for Bituminous. Converted to PRB

1994•Blend coal 85% PRB, 15% Bailey , y•NOx control: OFA & SCR installed 2003•SO2 control (Proposed FGD 2018)

•There were NO Injuries with this incident•This presentation is in part to give back to the PRB group that has served as a valuable g presource

– PRB Users Group p• “To establish best practices for the SAFE operation

and maintenance of PRB coal handling and storage t b d b t il bl t h l i ”systems based on best available technologies”

COMBUSTIBLE DUSTDespite the very high temperatures developed within a fire it is not an explosionDespite the very high temperatures developed within a fire, it is not an explosion. Two other conditions must be satisfied in order to ascend to an explosion status. These are: dust dispersed in the necessary cloud concentration and a confinement of the dust cloud within an area. The explosion pentagon provides a representation p p g p pof these conditions.

Counter weight/belt

Heat from bend roller/Shaft

Take up tower enclosure

EXPLOSIONS – CAUSES ANDEXPLOSIONS CAUSES AND EFFECTS

Housekeeping/Scaffolding Oxygen

The three constituents for fire still remain: oxygen, fuel and ignition as depicted on th fi t i l B h i th f l il bl d t l d d h i th d tthe fire triangle. By having the fuel available as a dust cloud and having the dust cloud contained within a vessel or room, all of the conditions required for an explosion are present.

Timeline of events

•On January 8, 2009 the coal handling department was in the process of dumping 57 coal cars to the coal bunkers, storing out to the storage pile, and blending in a medium-sulfur coal. •8:30 AM The C 8 belt was briefly shut down while two coal handlers cleaned•8:30 AM - The C-8 belt was briefly shut down while two coal handlers cleaned the coal out of the table and rollers at the bottom. •10:30 AM - C/H Rover was at the tripper floor (top of C-8) noted fire doors closed on C-8 and upon opening them and looking down he noted nothing out ofclosed on C 8 and upon opening them and looking down he noted nothing out of the ordinary (see, smell or hear)•11:30 AM - Coal handlers finished cleaning coal spill at bottom of C-8, nothing noted out of the ordinary•1:30 PM - C/H Supervisor toured the bottom of C-8 to inspect clean up. Nothing noted out of the ordinary•4:30 PM - Bunkers full, C-8 Shut Down. Coal continued to the store out system•4:40 PM - All conveyors were emptied and shut down•4:45 – 5:24 PM - several employees left & reported for work many parking by the C-8 take up tower, nothing noted out of the ordinary

Timeline of events continued

•5:25 PM - Numerous employees felt and heard an e plosionexplosion.

– Safety Supervisor heard two explosions in rapid succession saw a bright flash and felt radiant heatsuccession, saw a bright flash, and felt radiant heat from his office windowsThe siding on the north side of the C 8 conveyor– The siding on the north side of the C-8 conveyor take-up enclosure had opened. Fire was burning in the C-8 take-up enclosure and began moving rapidly p g g p yup the conveyor towards the plant

5:27 PM – The fire department log indicates call received

•5:32 PM Station Operator noted that there was fire in the entire C-8 conveyor all the way up to the plant. (Fire Protection not activated yet)

South take up bend roller/shaft shifted into the conveyor tableshifted into the conveyor table frame

Misalignment switch?Misalignment switch?

It is believed that a cloud of dust provided the fuel for the explosion. The dust cloud was created by eitherThe dust cloud was created by either the impact of the tensioning weight hitting the floor or by the belt’s violent movement at separation. The dust filled the take-up enclosure and exploded when it reached its ignition source

Timeline of events continued

5:30 PM – The fire department log indicates fire k i i h ltrucks arriving at the plant

– Station employees assist fire department to locate fi h dfire hydrants

– A short delay (~15 minutes) was experienced h th Fi D t t h d t did twhen the Fire Department hose adapter did not

arrive on the first truckOperators shut off the dust collectors– Operators shut off the dust collectors

Timeline of events continued

•Efforts to keep fire from entering the plant– C-9 deluge valve (tripper floor) tripped supplyingC-9 deluge valve (tripper floor) tripped, supplying

water to the fire protection sprinkler heads.– Other station employees began to stage fire fightingOther station employees began to stage fire fighting

equipment and hoses in advance for the fire department efforts

– The bunker area was non-accessible without SCBA’s (Limited Visibility)

•5:35 PM – C-8 fire protection system activated

5:45 PM –Fire sprinkler header had pulled apart about 100 feet north of the take-up enclosure.

5:50 PM – Fire department starting applying water to the conveyor fire

Fire Break Area (section of conveyor open, no siding)

Timeline of events continued

•5:50 PM – Operations Supervisor reported he heard a quenching sound near the top5:50 PM Operations Supervisor reported he heard a quenching sound near the top of C-8 and the fire started to die down. Firemen fought the fire from the top of C-8 and at the take-up enclosure on the ground until it was extinguished•6:17 PM – The fire department reported the fire was under control.p p•7:57 PM – The fire department reported fire out. •~10:00 PM – Contractor reported seeing flames on the tripper floor dust collector. The fire protection system was set off manually by the Operations Supervisor•11:00 PM- Tripper floor dust collector fire reported to be out by the Michigan City Fire Department.

SEVERE STRUCTUAL DAMAGE

SEVERE STRUCTUAL DAMAGE

•All components stripped out prior to lifts

•Weather (high winds) big factor with ( g ) glifts (several delays)

Severe structural damage (fire) and 35 years of corrosion

Scaffolding installed to support sections 3 & 4

New conveyor sections were fabricated off site & shipped with all internal components installed

Fire Exits added

Washdown control panel (16 zones)

Fire detection and suppression ppwashdown system

CO Monitoring (bunkers were g (existing). Added CO on conveyor

Washdown Nozzles spray entire conveyor structure

Drains for Washdown (inside)

Modifications on side walls to prevent hideout places

Drain collection from floor inside

Wash down drains final collection Upper sections,

belt water collection, and lower sections

RECOMMENDATIONS (Actions Taken)• Housekeeping

– Next day cleaning schedule developed from Rover and Supervisor round sheet– Installed an efficient and effective wash down system on C-8 conveyor

Helper classification added (cleaning with equipment off)– Helper classification added (cleaning with equipment off)• Several conveyor systems have been repaired/upgraded

– Conveyor Systems (belt conditions & tracking) high priority• Electrical trip devices (misalignment & trip cords) verified to be operating properly• Electrical trip devices (misalignment & trip cords) verified to be operating properly• Operating Procedures revised

– Rover round sheet and duties revised – Post walk-downs by coal handling personnel at end of the shift (equipment off)y g p ( q p )– Reinstated walk-down of conveyor systems between 7:00 & 9:00 PM each day by security

• Combustible Dust Assessment entire coal fleet @ NIPSCO (final reports issued March 2010).

• Employee training on combustible dust• Employee training on combustible dust.• Fire protection systems• Local Fire department tours and equipment gang boxes stored @ tripper floor• CO MonitoringCO Monitoring

THANK YOUTHANK YOU

QUESTIONS