Institute of Paper Science and Technology In Situ Causticization for Black Liquor Gasification: Feasibility, Development, Economics, and Mill Integration.

Institute of Paper Science and Technology

In Situ Causticization for Black Liquor Gasification: Feasibility,

Development, Economics, and Mill Integration

Principal Investigator: Scott Sinquefield, IPSTCollaborators: Ingrid Nohlgren and Jeff Empie, IPST

Daniel Centempo, Jacobs Engineering GroupConsultant: 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

– Autocausticization• causticization with a soluble mixed oxide, eg BO2

Autocausticization means ”self-causticization”, i.e. The pulping alkali causticizes itself during the combustion or gasifiction

– Direct causticization• 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 (Na2O3TiO2) (s) 3 (4Na2O 5TiO2) (s) + 7 CO2 (g) – In leaching unit:

3 (4Na2O 5TiO2)(s) + 7 H2O 14 NaOH (aq)+5 (Na2O3TiO2) (s)

• The kinetics has been shown to be fast enough to occur within a HTBLG system (900-1000C, 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 – 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:

– In gasifier:

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 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 – 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• 400-1100C• 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• 600-1500C• 2-80 bar• black liquor solids flow :

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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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)

– Member companies allocate their dues toward the consortiums of greatest interest

– 9 companies make up the gasification consortium

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IPST Gasification program(Elective Research Consortia)

• Personnel– 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:– 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)

– Black Liquor Gasification with Borate Autocausticization (funded by US Borax and IPST ERC)

– An External Benefits Study of Black Liquor Gasification (3-year Sloan Foundation, GIT Prof. Michael Farmer, started July 2002)

– In Situ Causticization for Black Liquor Gasification: Feasibility, Development, Economics, and Mill Integration (3-year DOE-funded, Jacobs Engineering, starting Sept 2002)

– 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):

– Development and Optimization of Catalysts for the Destruction of Tars Formed in Black Liquor/Biomass Gasification

(GIT – Pradeep Agrawal (prime))

– 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)

– 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 modified pulping studies and BLG mill integration research