Transcript In situ Causticization for Black Liquor Gasification

In Situ Causticization for Black
Liquor Gasification: Feasibility,
Development, Economics, and
Mill Integration
Principal Investigator: Scott Sinquefield, IPST
Collaborators:
Ingrid Nohlgren and Jeff Empie, IPST
Daniel Centempo, Jacobs Engineering Group
Consultant:
Honghi Tran, University of Toronto
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Project data
 Sponsor: U.S. Department of Energy
(Agenda 2020)
 Level of Funding: $ 600,000
 (DOE: $480,000 and IPST: $120,000)
 Period of Perfomance: Sept 2002-Aug 2005
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Background
 One of the gaps identified on the Peachtree Summit
(May 2001) was the increased causticization load for
both high and low temperature gasification compared to
conventional technology
 Alternative causticization processes, such as in situ
causticization, would be possible gap filling technologies
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In situ causticization
Addition of a chemical agent to the black
liquor, which reacts directly in the gasifier
with the sodium to form a salt and thus
allow the carbon to be released as CO2
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In situ causticization
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Autocausticization
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causticization with a soluble mixed oxide, eg BO2
Autocausticization means ”self-causticization”, i.e. The pulping
alkali causticizes itself during the combustion or gasifiction
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Direct causticization
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causticization with an insoluble metal oxide, eg TiO2
The causticization agent is added and subsequently removed,
and added again...
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Overall objective
Testing and evaluation of three in-situ
causticization processes at realistic gasifier
conditions for feasibility of partial and
complete in situ causticization during black
liquor gasification.
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The three in situ causticization processes
 Direct causticization using titanates
 Direct causticization using manganates
 Autocausticization using borates
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Direct causticization using titanates
 Main reactions:
In gasifier:
7 Na2CO3 + 5 (Na2O3TiO2) (s)  3 (4Na2O  5TiO2) (s) + 7 CO2 (g)
 In leaching unit:
3 (4Na2O  5TiO2)(s) + 7 H2O  14 NaOH (aq)+5 (Na2O3TiO2) (s)
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 The kinetics has been shown to be fast enough to occur
within a HTBLG system (900-1000C, pyrolysis and CO2
gasification)
 A number of studies have shown that titanates will causticize
sodium carbonate under conditions relevant to LTBLG
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Direct causticization using manganates
 Main reactions:
 In gasifier:
Na2CO3 + Mn3O4  2 NaMnO2 + MnO + CO2
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In leaching unit:
2 NaMnO2+ MnO + H2O  2NaOH(aq) + Mn3O4
 Previous work has shown that addition of Na2S led to
oxidization to Na2SO4, however no metallic sulfide (MnS)
was found
Na2S + 4 Mn3O4  Na2SO4 + 12MnO
 Only study at LTBLG
 Will H2S released during LTBLG react to form MnS?
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Autocausticization using borates
 Main reactions:
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In gasifier:
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NaBO2 + Na2CO3  Na3BO3 + CO2
Hydrolysis:
Na3BO3 + H2O  2NaOH(aq) + NaBO2 (aq)
 Earlier work focused on recovery boiler operation
 Borates are alkaline soluble  dead load  partial
autocausticization
 Potentials for LTBLG or HTBLG?
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Objectives
 Determine if any of the in situ processes studied can
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achieve a high yield of causticization or an acceptable
degree of partial causticization for each BLG
technology (HTBLG/LTBLG)
Evaluate each of the successful causticization
technologies during repeated recycling of the
causticizating agent
Identify viable methods of purging dregs
Resolve the technical barriers to commercialization
and mill integration
Perform a complete techno-economical evaluation of
the processes selected.
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How we plan to accomplish the work
 Phase 1:
Experimental testing at realistic BLG
conditions of the in situ causticization
technologies
 High
temperature borate and titanate cases will be
evaluated using the pressurized, entrained-flow reactor at
IPST
 Low
temperature experiments with borate, titanate and
manganate will be carried out at IPST using a semi-batch
fixed bed reactor
In all cases, the goal is to gasify the liquor/agent mixtures
under conditions representative of the industrial gasifiers
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Phase 1 - Tasks
 Thermodynamic modelling using FactSage (titanate, manganate
and borate)
 HTBLG of borate doped liquor and titanate doped liquor respectively
under oxygen blown, and water vapor, pressurized conditions
(950˚C, 5 and 15 bar)
 Evaluation under LTBLG conditions using water vapor
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Titanates: (600˚C & 800˚C, 1 bar)
Manganates: (600˚C, 1 bar)
verify that the causticization and gasification reactions proceed in
parallel and that H2S gas does not react with Mn3O4 during
gasification
Borates: (600˚C, 1 bar)
 Hydrolyze the solid products and characterize the insolubles
(manganates)
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How we plan to accomplish the work
 Phase 2:
The processes that pass phase 1 will be
developed for potential ways of purge dregs.
Tasks:
 Characterization of the dregs from successful processes
 Identify and evaluate feasible ways of purging dregs, examples:
 selective dissolution
 filtration
 liquid cyclones
 addition of agglomerating agents.
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How we plan to accomplish the work
 Phase 3:
The processes that pass phase 2 would undergo
an economic evaluation including a plan for
mill/gasifier integration
Tasks:
 Assess the economics of all processes that pass phase 2
 Mill integration requirements for causticization processes for
both high and low temperature BLG, and for both partial and
complete in situ causticization
This will be done by Jacobs Engineering Group with the support
of all collaborators as needed
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Facilities at IPST
 Laminar Entrained Flow Reactor (LEFR)
 Pressurized Entrained Flow Reactor (PEFR)
 Fixed bed reactors
 Analytical:
 2 FT-IR’s, GC, Duo-Titrator, NO/NO2
 (Mass Spec coming soon)
 Chemical Analysis group on site
(SEM, XRD, MS, ICP, etc.)
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LEFR
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400-1100C
1 bar
black liquor solids flow :
0.1-0.5 g/min
Primary gas flow rate: 0.1-1 l/min
Secondary gas flow rate:
2-40 l/min
Reaction gases: N2, O2, H2O (v),
CO2, H2, CO, CH4, SO2, H2S.....
Steam flow rate: 0.2-6 g/min
 Residence times up to 3 sec with movable quenching collector
 On-line FT-IR and NOx analysers
 Filter for fume collection
 3 micron cyclone for char collection
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PEFR
 600-1500C
 2-80 bar
 black liquor solids flow :
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0.1-30 g/min
Primary gas flow rate:
1 - 5 l/min
Secondary gas flow rate:
25-500 l/min
Reaction gases: N2, O2, H2O (v), CO2,
H2, CO, CH4, SO2, H2S.....
Steam flow rate:
0.1-170 g/min
Residence times up to 8 sec with
movable quenching collector
On-line FT-IR and NOx analysers
Filter for fume collection
2 micron cyclone for char collection
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Pressurized
EntrainedFlow
Reactor
Fixed bed reactor
 Sample boat in a ceramic tube in a tube
furnace
 Feed gas composition chosen to
approximate the product gas composition
from an industrial gasifier
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IPST Gasification program
(Elective Research Consortia)
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Member companies allocate their dues toward
the consortiums of greatest interest
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9 companies make up the gasification consortium
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IPST Gasification program
(Elective Research Consortia)
 Personnel
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Dr. Scott Sinquefield (program leader)
Prof. Ingrid Nohlgren
Prof. Jeff Empie
Dr. Chris Verrill
Dr. Xiaoqun Wu (Post-Doc)
Xiaoyan Zeng (Post-Master)
Alan Ball (Sr.Technician)
Jennifer Mattews (MS student)
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IPST Gasification program
(Elective Research Consortia)
Subprograms:
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Stability and Regenerability of Catalysts for Destruction of
Tars Formed during Black Liquor and Biomass Gasification
(3-year DOE funded, GIT Prof. Pradeep Agrawal, ending Feb, 2003)
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Black Liquor Gasification with Borate Autocausticization
(funded by US Borax and IPST ERC)
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An External Benefits Study of Black Liquor Gasification
(3-year Sloan Foundation, GIT Prof. Michael Farmer, started July 2002)
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In Situ Causticization for Black Liquor Gasification:
Feasibility, Development, Economics, and Mill Integration
(3-year DOE-funded, Jacobs Engineering, starting Sept 2002)
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Black Liquor Gasification Kinetics
(On-going research. Funding levels TBD)
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IPST Gasification program
(Elective Research Consortia)
DOE Proposals (April 2002 solicitation):
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Development and Optimization of Catalysts for the Destruction of
Tars Formed in Black Liquor/Biomass Gasification
(GIT – Pradeep Agrawal (prime))
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An Experimental Investigation of the Chemical Processes in
High-Temperature Pressurized Gasification of Black Liquor
(IPST(prime), Chalmers – Hans Theliander, Jim Frederick, Kristiina
Iisa, GIT – Pradeep Agrawal)
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Integrated Sulfur Recovery and Causticization for Black Liquor
Gasification
(U of Maine, A. van Heiningen (prime), U of Utah - K. Whitty,
Weyerhaeuser - C. Brown and IPST)
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Collaboration potentials?
 The pressurized gasifier (PEFR) at IPST is a unique and
versatile facility for gathering kinetic data for
creation/validation of kinetic models of pyrolysis,
gasification, and combustion
 IPST is an integrated pulp and paper research facility; an
ideal site for the combination of modified pulping studies
and BLG mill integration research
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