Fuel Flexibility with Biomass for
Coal Boilers at University of Iowa
Ben Anderson – University of Iowa
Andy Ungerman – Stanley Consultants
Agenda
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Introductions
Overview & Biomass Initiatives
Permitting Strategy
Project Design & Biomass Considerations
Project Construction
Startup & Lessons Learned
Future Plans
Conclusions & Questions
Introductions
• Ben Anderson – University of Iowa
– Power Plant Maintenance & Engineering Manager
– BSME from Iowa State University
– Petro-chemical background
• Andy Ungerman - Stanley Consultants
– Mechanical Engineer – Energy Business Group
– BS & MSME from Iowa State University
– Power Plant Consulting Background
Overview
• University of Iowa – Main Power Plant
– 4 Boilers: 600+ klb/hr, 3 Turbine Generators - 24.7 MW
135,00 lbs/hr
140,00 lbs/hr
– 6 offsite natural gas and 1 biomass boilers
Biomass Initiative
• University of Iowa - Biomass Initiative
– Achieve the goal of 40% renewable energy consumption on the
campus by 2020
– More info at http://sustainability.uiowa.edu/biomass/
Permitting Strategy
• BLR 10 Biomass
– IDNR to issue permit on 12/2011, failed PM 10 test, permit closed
– New permit submitted several months ago
• Wood chips, yard trimmings, paper sludge – Cedar Rapids Landfill & other local sources
• Update with Fuel grasses – miscanthus
• Expect approval in next month
– Increased reporting
• Track fuels usage
• Frequent fuel sampling (ensure below PSD for NOx, SO2, and PM2.5)
• BLR 11 Biomass
– Current permit for oat hulls
– Approved variance to burn wood chips
• Collaboration with state park to dispose of 2500 tons of pine
• Plan to have permanent change submitted in early February
• Plant wide Applicability Permit (PAL) submitted to IDNR
Project Design - Overview
• Replace “dense” phase coal handling system
with 30 TPH belt conveyor
• Provide provisions for future biomass or PRB
• Original plant – 1926
• 3D scan converted to 3D Model
Project Design - Overview
~16° incline,
tubular gallery
Compact, cartridge
dust collectors
75 ton bunker
(8 hr supply)
Equipment
located for
future biomass
equipment
Gravimetric
feeder w/
conical
distributor
Completely
insulated enclosures
and galleries
Extensive
reinforcement and
modification to
existing structures
Project Design: Co-firing with Biomass
UT Distributors for Biomass
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Woodchip/Biomass issues – non uniform sizing1
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Volumetrically limited – Max 15% Biomass (soft number) –
assuming sizing is similar1
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15% vol blend = 6% by weight = 3% by BTU
(assuming woodchip density of 20 lb/ft3, and a heating
value of 4,500 Btu/ft3)
Closer the properties to coal, higher the percent1 – 100%?
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Pelletized or torrified wood etc.
Non-Segregated Distributor
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Woodchip/biomass issues – non uniform sizing
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Different sizing may lead to segregation
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Lack of data on biomass
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Closer properties are to coal, the better
1Per
information received from Detroit Stoker Corp, used with permission.
Project Design: Co-firing with Biomass with Stoker Boiler
Air swept spouts
Best Arrangements for Co-Firing Wood1
• Separate fuel trains
• Different fuel sizing = separate trains
• Goal is to get good ash bed on grate and uniform distribution
• Symmetry is important! UTs 1 and 5 or 2 and 4
Combo Feeders1
• 1000 lbs/in of feeder (Qty 2 feeders = 54 kpph)
• Recommended fuel drop height = 10 ft
• Distributes fuel lower in furnace (preferred)
• Requires header to be moved
Combo Feeders
Air swept spouts1
• 50% of grate to be covered with spouts (20’ grate requires
four 30” air spouts)
• Location = higher in furnace
• Tube bending vs. moving header
• Must get around non-seg distributor
1Per
information received from Detroit Stoker Corp, used with permission.
Future Biomass Flexibility at UOI
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Unique design – grav. feeder w/ non-seg dist.
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75 ton (coal) bunker can be offset further
compared to batch-type feeder.
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Allows emergency unloading
Future biomass robbing screws and hoppers
can be fed by a “surge bin” fed from a
separate material handling system using a
new silo
Detroit Stoker UT Distributor hoppers modified
to allow for future Combo feeders.
Bunker could be modified to bottom reclaim
(remove bottom cone)
75 Ton Bunker
Drag chain
Surge hoppers &
robbing screws
Future
Feeder/Non Seg Offset
UT hoppers allow
for future Combo
feeders.
Comparison of Fuels and Mat’l Handling for Boiler 10
Boiler 10 MCR Steam Flow, lb/hr
Boiler 10 Fuel Flow, MMBtu/hr
Approx. Heating Value, Btu/lb
Boiler 10 Fuel Flow, ft3/hr
Conveyor Capacity, tph
Conveyor Belt Speed, fpm
Belt Loading, %
Conveyor Capacity, ft3/hr
Time to Empty Bunker w/ Boiler 10 at MCR, hr
Stoker Wood
Coal
Chips
170,000 135,000*
213.6
204.2
11,600
4500*
368
2,269
35
25
100
125
58
80
1400
2500
8.1
1.3
85% Coal
15% Wood
(Volume)
170,000
213.7
11,131
422
31.8
100
67
1600
7.1
* Heat input and Heating value taken from Biomass Conversion Study Report (2010) for UOI by Riley
Power. Used with Permission.
Project Construction
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Logistics
Equipment Fabrication
Crane - Gallery & Conveyor install
Boiler Shutdown and Dense Phase Demo
Start-up & Lessons Learned
Project Construction – Logistics
• Iowa River
• Campus Location
• Space Constraints
– Equipment laydown
– Contractors
Project Construction – Equipment
Fabrication
• Schedules
• Manufacturing visits
• Delivery
Project Construction - Crane
• Logistics – 20+ semi
tucks
• Ground survey
– Voids
– Flat surface
• Crane location &
continued plant ops
Project Construction - Installation
Project Construction - Installation
Project Construction - Boiler
Shutdown & Dense Phase Demo
• Major 3+ month outage
– Boiler maintenance
– Boiler lay-up
• Planned start-up on
11/30/12
• Back-up boiler installed
Start-up & Lessons Learned
• Permitting & Construction Timing
• Commissioning & Training
• CHS operational - several nuisance trips
– Alignment switches; belt tracking
– CO monitors
– VFD Fault on gravimetric feeder
– Plugged conveyor
• Alarm Rationalization (CO, Alignment switches)
• Cleanliness
Future Plans
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Full inspection and baseline on boiler (complete)
Burn wood chips in near future (ASAP)
Begin developing test runs for other fuels (Ongoing)
Installing natural gas burner Spring 2013
Internal inspection at regular intervals (Ongoing)
Modifications to fuel handling system for increased
Biomass combustion
Conclusions
• Develop solid Biomass plan
• Design projects to be flexible for future
conversions
• Work on permitting strategy early and plan for
good discussions
• Complete equipment scenario/what-if analysis
and implement into planning/design
Questions