Hot Oxygen Injection
into the Blast Furnace
The Eastern States
Blast Furnace
& Coke Oven Association
Winter Meeting 2008
Copyright © 2016, Praxair Technology, Inc. All rights reserved.
www.praxair.com/metals
Motivation for Increased
Coal Injection (PCI)
• Injecting pulverized coal to displace coke,
lowers costs
• Requires oxygen enrichment to maintain flame temperature
• Operating problems at high PCI rates
• Incomplete coal combustion leading to
• Carbon dust in off-gas
• Increased furnace pressure drop
• Need better pulverized coal combustion
for higher PCI rates
2
What Conditions Favor the Most Rapid
Combustion of Pulverized Coal?
• High Oxygen Concentrations
• High Temperatures
• Thorough Gas / PCI Mixing
3
Hot Oxygen Injection
• High-temperature oxygen jet
• High oxygen concentration
• High temperature
• High momentum (enhanced mixing)
• Hot oxygen injection with blast furnace
coal
• Faster ignition
• More complete burnout
• Ability to sustain higher coal injection rates
4
Praxair “Thermal Nozzle”
for making Hot Oxygen
U.S. Patent 5,266,024
Oxygen
Fuel
Hot
Oxygen
Jet
5
Hot Oxygen Lance in Laboratory
6
Hot Oxygen Chemistry
Oxygen
Temperature
°F
Product
Reactant
Composition
Oxygen
100 scf
2500
Natural Gas
6.4 scf
Oxygen
100 scf
3000
Oxygen
81.9
Carbon Dioxide
6.0
Water Vapor
12.1
Oxygen
Carbon Dioxide
Natural Gas
8.2 scf
Percent
Water Vapor
Sonic
Velocity
ft/s
2,450
77.1
7.6
2,647
15.0
7
Advantages of Praxair’s
Hot Oxygen Injection
Ambient Injection
• Turbulence
Hot Injection
• Turbulence
• Sonic velocity 1100 ft/s
• Sonic velocity 2600 ft/s
• Cold Oxygen / Cold Coal
• Hot Oxygen / Cold Coal
• Slow heating
• Low volatile release
• Need blast mixing for ignition
• Low Oxygen
Concentration at Ignition
• Rapid heating
• High volatile release
• Ignition without dilution
• Oxygen Concentration
~80% at Ignition
8
Hot Oxygen Lance Mounted in
Blowpipe
Hot Oxygen Lance
Tuyere
Blowpipe
Coal Lance
9
Hot Oxygen Lance Mounted in
Blowpipe
Hot Oxygen Lance
Tuyere
Blowpipe
Coal Lance
10
Pilot Scale
and Industrial Testing
• Pilot Scale PCI Combustion Studies Performed
at Canmet Energy Technology Center
• Burnout and volatile matter release tests conducted on hivolatile and low-volatile coals
• Thermogravimetric analysis char samples to determine
reactivity
• Two-Tuyere tests at USS Gary #6
• AISI/DOE Technology Roadmap Program
• Determine furnace compatibility and industrial robustness
11
Pilot Test Results
• CANMET Pilot Scale Tests
• Pilot scale blowpipe thermo-gravimetric reactor with
simulated raceway atmosphere
• High-volatile pulverized coal (Gary) and low-volatile granular
coal (Burns Harbor)
• Compared: oxygen enrichment, ambient oxygen injection,
hot oxygen
• Burnout with hot oxygen 20%-50% greater than other
routes
• Hot oxygen generated char also the highest reactivity
12
Pilot Scale Results
U.S. Steel high-volatile pulverized coal
Coal burnout
Char reactivity
pct
100
3.0
pct loss/min
2.5
80
Hot
2.0
60
Ambient
Enrichment
1.5
Base
40
1.0
20
Tuyere coke
0.5
0
0.0
7.5
9.5
Coal injection rate, kg/h
5
2
Raceway oxygen, pct
13
USS Gary Works Two Tuyere
Industrial Trials
• No adverse effects on hardware or operation
• Blowpipe surface temperature unchanged
• Tuyere heat load increased 10%
• Enhanced coal combustion observed
• Blowpipe / tuyere pressure measurements suggest
hot oxygen gives 30% increase in initial burnout
• Results in line with CANMET results
• Ignition within lance combustion chamber critical
• Lance performance
• Ignition reliability >85% achieved with modified lance materials,
ignition practice
• No significant lance degradation over 30 day operating period
14
Primary Economic Benefit:
Coke Savings
• Increased and sustained PCI injection
rates of up to 75 lbs per ton of hot metal
Unit Cost, $/Ton or $/MCF
Improvement with Hot Oxygen
Conventional Coal injection with O2
Hot Oxygen Benefit
100
Coal
lbs/thm
385
310
250
Coke
lbs/thm
641
708
40
8
Oxygen Natural Gas
MCF/THM MCF/THM
Cost
Savings
3.2
0.208
$ 106.28 $ 18.72
0.166
$ 109.63 $ 15.37
2.6
$
3.36
15
Estimated Savings vs. Coke Price
$25,000,000.00
$14.00
$22,500,000.00
$ THM
$12.00
$20,000,000.00
$17,500,000.00
$10.00
$15,000,000.00
$8.00
$12,500,000.00
$6.00
$10,000,000.00
Assumptions:
Ï 5000 TPD Production
Ï Increased PCI by
75lbs/THM
Ï PCI: $100/ton
Ï Oxygen: $40/ton
Ï Natural Gas: $8/MCF
$4.00
$2.00
$0.00
200
250
300
350
400
450
$7,500,000.00
$5,000,000.00
Estimated Annual Savings
Savings ($/short ton Hot Metal)
Annual Savings
$2,500,000.00
$0.00
500
Coke Price ($/ston)
16
Other Potential Benefits
• Productivity Benefits
• As a result of the increased oxygen in the hot blast, an
increase in productivity of approximate five percent is
expected.
• Higher BTU Top Gas
• Models predict approximately a 5 BTU per cubic foot
increase in top gas heating value
• Net Savings in CO2 emissions
• Savings for this scenario expected to be in excess of 35 lbs
of CO2 per ton hot metal
17
Recent Praxair Laboratory
Developments:
Lance Ignition Optimization
18
Hot Oxygen Lance Ignition Modes
Internal Ignition (proper operation)
External Ignition
19
Laboratory Test Apparatus, 2000°F air
(Simulated Hot Blast)
Phase Lance Optimization
20
Hot Blast Only Before Ignition
21
Hot Oxygen Lance in Simulated
Hot Blast (2000°F air)
22
Hot Oxygen Firing Video
This image cannot currently be displayed.
23
Conclusions
• Pilot scale studies show that substantially
improved pulverized coal combustion can
be achieved using Praxair’s Hot Oxygen
Technology
• Initial industrial trials demonstrated the
technologies mill worthiness and furnace
compatibility
• Praxair looks forward to proving projected
coke savings in a full furnace installation
24
Questions?
25