Transcript 2005 OBP Bi-Annual Peer Review Project Presentation Template

2005 OBP Bi-Annual Peer Review
In situ Causticizing for Black Liquor Gasifiers
Scott Sinquefield, IPST
Xiaoyan Zeng, IPST
Alan Ball, IPST
James Cantrell, Jacobs Engineering
Thermochemical Platform
November 15, 2005
Overview
Barriers
Timeline
• Project start: Oct 1, 2002
• Project end: Oct 31, 2006
• 70% complete
• Process Integration
• Validate integrated black liquor
gasification and causticiziation
processes.
Detailed
Investigation
Budget
• $600,000
• DOE $480,000
• IPST/Jacobs $120,000
• Funding in FY04: $137,402
• Funding for FY05: $165,605
• Requested FY06: $176,978
Partners
• Institute of Paper Science at
GA Tech
• Jacobs Engineering
Impetus
Both of the current, actively marketed, black liquor gasification technologies
results in an increased causticizing load which must be addressed
Entrained-flow gasifier
950C, O2- or air-blown,
~5 sec residence time
Steam reformer
~600C, fluidized bed
~50 hrs residence time
Project Goals and Objectives
• Phase 1: Direct- and auto-causticization processes (i.e. borates,
titanates, and manganates) have been demonstrated effective on
pure Na2CO3 in the laboratory. We test the processes on black
liquor at realistic gasification conditions and determine which
chemistries hold promise. Both equilibrium modeling and
experimentation are employed. Successful processes move on
to phase 2. (IPST) Go/No go
• Phase 2: For the successful causticizing chemistries we confirm
that concentrated caustic can be recovered, suitable for a pulping
liquor (i.e. white liquor). We also identify feasible ways of purging
non-process elements (“dregs”). (IPST) Go/No go
• Phase 3: For the methods passing Phase 2 (if any), we
determine the most rational ways of integrating them into the mill
and perform economic evaluations. (Jacobs + IPST)
Project Strategic Fit
Black liquor gasification (BLG) promises significant market incentives such
as combined cycle power generation, syn-gas to chemicals, and high-yield
pulping synergies. However, pulping chemicals must still be recovered,
and the inherent increase in causticizing load must be addressed:
• Partial in situ causticizing would offset the load increase for a full scale
gasifier utilizing the existing lime cycle; while complete causticizing
would eliminate the petroleum-intensive lime cycle:
• A 1000 ton/day pulp mill uses 90,000 bbls/yr #6 fuel oil to fire the kiln.
(=$3.78 Million/yr at current prices)
• Total US kraft pulp production is 156,700 ton/day.
100% adoption = 14 Million bbls/yr fuel oil saved.
(=$650 Million/yr in fuel saved)
• BLG for incremental capacity on a boiler-limited mill will require
equivalent incremental causticizing capacity.
• Pilot demonstration is easy with either a gasifier or a recovery boiler
• IPST membership includes P&P companies committed to BLG
Project Approach
Chemistry for the titanate case; others are analogous
Sodium is bound up by titanates within the gasifier:
Na2CO3+3 TiO2(s)  Na2O.3TiO2(s)+CO2 (g)
7Na2CO3+5(Na2O.3TiO2)(s)  3(4Na2O.5TiO2)(s)+7CO2(g)
Na2O6TiO2(s)+Na2CO3(s) 2(Na2O3TiO2)(s)+CO2(g)
[Abbreviated NT3, N4T5, NT6]
The caustic is later recovered by hydrolysis:
3(4Na2O.5TiO2)(s)+7H2O  14NaOH(aq) + 5(Na2O.3TiO2)(s)
2(Na2O3TiO2) (s)+H2O  2NaOH (aq)+Na2O6TiO2 (s)
Project Approach cont.
Phase 1
We begin by gasifying mixtures of
black liquor and the causticizing
agents (titanate, borate and
manganate) at industrially realistic
gasification conditions (i.e. entrained
flow at 950C, and steam reforming at
600C) and determine which
chemistries work. We also employ
equilibrium modeling with FactSage
5.1 for comparison.
Causticizing conversion is
determined by the carbonate content
remaining in the char (solid) phase
compared to char from un-doped
liquor.
IPST’s Pressurized Entrained Flow
Reactor (PEFR) was built for
gasification research in a variety of
gas environments at pressures to
30 bar, temperatures to 1500C,
and residence times to 8 seconds.
Project Approach cont.
Phase 2
The gasified char is hydrolyzed to recover the caustic. The leachate
solution is analyzed by ICP for metal species, and titrated to verify the
amount of hydroxide. The leached solids are characterized by SEM-EDS,
XRD, ICP, and BET to close the material balance and narrow the dregs
removal options between chemical and physical processes; then test.
Air, O2,
steam
Gasifier
Raw Syn
Gas
Char
Black
liquor
Leaching
Mixing
Cleaned
Titanate or
Manganate
Leached
solids
Dregs
Purge(?)
Raw
White
Liquor
Dregs
Purge(?)
White
liquor for
pulping
Project Approach cont.
Phase 3
The final phase includes mill integration and economic evaluations by
Jacobs Engineering
EQUIPMENT VENDOR INPUT
EQUIPMENT VENDOR
PROPOSALS
DESIGN BASIS
EXPERIMENTAL DATA
PROCESS SCOPE
DEVELOPMENT:
PROCESS DATA
ACQUISITION
MILL CHARACTERIZATION
WinGEMS AND/OR
EXCEL MATERIAL
AND ENERGY
BALANCES
-FLOWSHEETS
-EQUIPMENT LAYOUTS
-EQUIPMENT LIST
OPTIONS MODELS
± 25% CAPITAL
ESTIMATE
DISCIPLINE INPUT
ESTIMATING INPUT
Project Approach cont.
Phase 3
Economic evaluation
FUEL COSTS
UTILITIES COSTS
FUEL COSTS
UTILITIES COSTS
BLG W/
CONVENTIONAL
CAUSTICIZATION
OPERATION COSTS
ANALYSIS
ECONOMIC ANALYSIS
(NET PRESENT VALUE
COMPARISON)
BLG W/
DIRECT OR AUTO
CAUSTICIZATION
OPERATION COSTS
ANALYSIS
MILL INTEGRATION
STUDY REPORT
DIRECT OR AUTO
CAUSTICIZATION
CAPITAL COST
Project Tasks
• Phase 1: We must first demonstrate a high degree of causticizing
conversion for each of the chemistries. 85% causticizing efficiency is
common for the current lime cycle technology. If not, we abandon the
option (Go/No go)
• Phase 2: We must then confirm that we can hydrolyze the char and
get hydroxide back. The causticizing agent must be in its starting
form to be used again. If not, we abandon the option (Go/No go).
Also the dregs must be removable from the cycle or they will
accumulate.
• Phase 3: For any processes that remain, they must be such that they
can be integrated to the mill and they must be economical or they
have little value to the industry. Jacobs Engineering assumes the
lead in this phase.
Project Collaboration
Collaboration and Tech Transfer
• Coordinate with BLG vendors/users to include in situ causticizng
in pilot trials and incremental capacity applications
• Publish results in open literature
• Jacob’s can utilize the design data on its gasification projects.
• Revisit overall BLG (Low Temp and High Temp) economics for
kraft mill applications incorporating results of viable in situ
causticizing. Should help with justification for incremental units
as well as replacement systems.
• Apply results to conventional recovery boilers for mills with
bottlenecked lime kilns. [Note that borates have application in
Tomlinson-based recovery systems as well]
• On-going exchange of results with Adrian van Heiningen (U. of
Maine) who leads a project focusing on titanates and high-yield
pulping for low temperature steam reforming.
Market & Customers
• Potential customers are pulp producers, bio-refineries,
and electric utilities with the intent of building, owning,
and operating a gasification-based recovery island with
combined cycle power generation while processing
pulping liquors for an adjacent pulp mill.
• Threshold for adoption is IRR=25% (Larson, et.al. ‘A Cost
Benefit Assessment of Black Liquor Gasification’, 2003).
Larson found the IRR to be 20%, but without considering
in situ causticizing, environmental benefits, energy
credits, or external social benefits.
Competitive Advantage
• In situ causticizing processes provide an additional economic
incentive for adoption of black liquor gasification, and therefore
have the same window of opportunity; that being that the
technology must be ready for deployment as aging recovery
boilers are replaced or undergo major rebuilds.
• Competing technologies are state-of-the-art Tomlinson
recovery boilers and the supposed “high efficiency recovery
boiler”. While compatible with conventional pulp mills, they do not
integrate well with multi-product biorefineries. Gasification offers
greater flexibility over a wide range of process/product variations.
• Market effects would include reduced demand for #6 fuel and
lime, and increased use of TiO2, and/or NaBO2, and/or Mn3O4
• With regard to economics, the savings in offset fossil fuel (#6
fuel oil) alone justifies the use of in situ causticizing.
Project Stage
In situ causticization processes have been proven in the lab to convert
Na2CO3 to NaOH. In this work we test them with black liquor at realistic
gasifier conditions, investigate non-process element removal, and perform
economic and mill integration evaluations. Are the processes truly viable?
Progress and Accomplishments
Results show that titanate direct causticizing will work for high temperature
black liquor gasification at low to moderate pressures, but not at 20 bars
(unless the CO2 can somehow be maintained at a lower level)
100%
% Carbonate Conversion
90%
80%
BLG w/Titanate for 100% Causticizing:
CO3 conversion in PEFR at 950C
70%
60%
50%
40%
30%
20%
Equilibrium
(FactSage)
prediction of
CO2 levels for
O2-blown BLG
above 5 bar
Equilibrium (FactSage)
prediction of CO2
levels for air-blown
BLG, 1-5 bar
10%
0%
0.0
0.5
1.0
CO2 Partial Pressure, Bar
1.5
2.0
Progress and Accomplishments
Titanate direct causticizing was not effective for the steam reforming case at
600C. However, modeling suggests that it would work at 650C and above.
100%
Carbonate Conversion
90%
BLG w/Titanate for 100% Causticizing:
CO3 conversion at 600C in steam + CO2
80%
70%
60%
50%
40%
Equilibrium (FactSage)
prediction of CO2 levels for
steam BLG (reforming) at
1.0 bar and above.
30%
20%
10%
0%
0
0.1
0.2
0.3
CO2 Partial Pressure, Bar
0.4
Progress and Accomplishments
Borates added for 20% conversion will be effective for atmospheric pressure
entrained flow gasification (such as the Chemrec booster at New Bern)
40%
BLG w/Borate for 20% Causticizing:
CO3 conversion in PEFR at 950C
% Carbonate Conversion
35%
30%
25%
Equilibrium (FactSage) prediction of
CO2 levels in product gas over
range of reasonable O2/Fuel ratios
for air-blown BLG at 1.67 bar.
20%
15%
10%
5%
0%
0.0
0.2
0.4
0.6
0.8
1.0
1.2
CO2 Partial Pressure, Bar
1.4
1.6
1.8
2.0
Progress and Accomplishments
Borates added for 20% conversion did not prove to be effective for the 600C
steam reforming case. Modeling suggests that 925C would be required.
40%
BLG w/Borate for 20% Causticizing:
CO3 conversion at 600C in steam + CO2
Carbonate Conversion
35%
30%
25%
20%
15%
Equilibrium (FactSage)
prediction of CO2 levels for
steam BLG (reforming) at
1.0 bar and above.
10%
5%
0%
0
0.1
0.2
0.3
CO2 Partial Pressure, Bar
0.4
Progress and Accomplishments
Manganates proved to be 100% effective for steam reforming at 600C,
but at 950C (not shown) they showed zero conversion
Gas Conditions
Fixed
(i.e. char)
carbon
in smelt
Experimental
causticizing
conversion
50%H2O
0.00%
100%
50%H2O
0.05%
100%
50%H2O
0.01%
100%
50%H2O+10%CO2
0.03%
95%
50%H2O+10%CO2
0.02%
100%
Progress and Accomplishments
Phase 2. Summary of non-process element removal results
• Concentrated caustic (white liquor) can be made but will
require staged leaching of titanate char
• Leaching of manganate chars consistently yielded 40% of
expected hydroxide. We are working to resolve the
discrepancy.
• Hydration of borate chars produced high caustic recovery
• ICP analysis of char, leachate, and leached solids produced
good material balance closure.
• Most of the B, Cr, Si, and V split to the leachate phase
• The remaining non-process elements favor the solid phase.
SEM-EDS will determine the number of phases
Progress and Accomplishments
Phase 2. Non-process element removal options
• Viable techniques depend on fate of NPE’s (i.e. dissolved
versus solid phase and number of solid phases)
• Ion exchange
• Mg(OH)2 complexing
• Acid titration
• Laminar air classification (size/density difference)
• Density-based separation for slurries
• APIC jig air pulses produce bed with density gradient
• Knelson/Falcon concentrators centrifugal
Future Work
• Further characterize the leached solids to determine how
non-process elements are distributed with respect to
phases. This will narrow the removal options to test
• Resolve the hydroxide material balance for the manganate
case. If hydroxide cannot be balanced with carbonate,
then must abandon this option.
• Test the chemical processes for non-process element
removal in the lab.
• Test borates at 100% conversion for HTBLG.
• Mill integration study, including: design basis, material &
energy balances, process scope descriptions, flow
diagrams, major equipment, +/-25% capital estimate.
• Economic evaluation.