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Release | : 2006 |
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Download Direct Causticization for Black Liquor Gasification Book in PDF, ePub and Kindle
This project is evaluating advanced pulping technologies which fully utilize the white liquors produced by the tocombined technology of steam reforming and direct causticization of black liquor.
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Release | : 2007 |
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Download Mill Integration-Pulping, Stream Reforming and Direct Causticization for Black Liquor Recovery Book in PDF, ePub and Kindle
MTCI/StoneChem developed a steam reforming, fluidized bed gasification technology for biomass. DOE supported the demonstration of this technology for gasification of spent wood pulping liquor (or 'black liquor') at Georgia-Pacific's Big Island, Virginia mill. The present pre-commercial R & D project addressed the opportunities as well as identified negative aspects when the MTCI/StoneChem gasification technology is integrated in a pulp mill production facility. The opportunities arise because black liquor gasification produces sulfur (as H2S) and sodium (as Na2CO3) in separate streams which may be used beneficially for improved pulp yield and properties. The negative aspect of kraft black liquor gasification is that the amount of Na2CO3 which must be converted to NaOH (the so called causticizing requirement) is increased. This arises because sulfur is released as Na2S during conventional kraft black liquor recovery, while during gasification the sodium associated Na2S is partly or fully converted to Na2CO3. The causticizing requirement can be eliminated by including a TiO2 based cyclic process called direct causticization. In this process black liquor is gasified in the presence of (low sodium content) titanates which convert Na2CO3 to (high sodium content) titanates. NaOH is formed when contacting the latter titanates with water, thereby eliminating the causticizing requirement entirely. The leached and low sodium titanates are returned to the gasification process. The project team comprised the University of Maine (UM), North Carolina State University (NCSU) and MTCI/ThermoChem. NCSU and MTCI are subcontractors to UM. The principal organization for the contract is UM. NCSU investigated the techno-economics of using advanced pulping techniques which fully utilize the unique cooking liquors produced by steam reforming of black liquor (Task 1). UM studied the kinetics and agglomeration problems of the conversion of Na2CO3 to (high sodium) titanates during gasification of black liquor in the presence of (low sodium) titanates or TiO2 (Task 2). MTCI/ThermoChem tested the performance and operability of the combined technology of steam reforming and direct causticization in their Process Development Unit (PDU) (Task 3). The specific objectives were: (1) to investigate how split sulfidity and polysulfide (+ AQ) pulping can be used to increase pulp fiber yield and properties compared to conventional kraft pulping; (2) to determine the economics of black liquor gasification combined with these pulping technologies in comparison with conventional kraft pulping and black liquor recovery; (3) to determine the effect of operating conditions on the kinetics of the titanate-based direct causticization reaction during black liquor gasification at relatively low temperatures ((less-than or equal to) 750 C); (4) to determine the mechanism of particle agglomeration during gasification of black liquor in the presence of titanates at relatively low temperatures ((less-than or equal to) 750 C); and (5) to verify performance and operability of the combined technology of steam reforming and direct causticization of black liquor in a pilot scale fluidized bed test facility.
Author | : Le Zeng |
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Release | : 1997 |
Genre | : Fluidized-bed combustion |
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Download Kraft Black Liquor Gasification and Direct Causticization with Ti02 in a Fluidized Bed Book in PDF, ePub and Kindle
Author | : Pratima Bajpai |
Publisher | : Elsevier |
Total Pages | : 103 |
Release | : 2014-03-06 |
Genre | : Technology & Engineering |
ISBN | : 0081000154 |
Download Black Liquor Gasification Book in PDF, ePub and Kindle
Black Liquor Gasification (BLG) is a first of its kind to guide chemical engineers, students, operators of paper plants, technocrats, and entrepreneurs on practical guidelines and a holistic techno-enviro-economic perspective applicable to their future or existing projects based on the treatment of black liquor for energy production. BLG describes the gasification process as a more efficient alternative to current processes for the conversion of black liquor biomass into energy. BLG operates largely in sync with other methods to improve pulp-making efficiency. This book explains how BLG offers a way to generate electricity and to reclaim pulping chemicals from black liquor, and why BLG would replace the Tomlinson recovery boiler for the recovery of spent chemicals and energy. Describes the utilization of black liquor as a source of energy Provides a detailed account of black liquor gasification processes for the production of energy and chemicals from black liquor Provides guidelines to chemical engineers for the treatment of black liquor
Author | : Le Zeng |
Publisher | : |
Total Pages | : 325 |
Release | : 1997 |
Genre | : Fluidized-bed combustion |
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Download Kraft Black Liquor Gasification and Direct Causticization with TiO22 in a Fluidized Bed Book in PDF, ePub and Kindle
Author | : Le Zeng |
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Total Pages | : |
Release | : 1998 |
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Download Kraft Black Liquor Gasification and Direct Causticization with TiO2in a Fluidized Bed Book in PDF, ePub and Kindle
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Release | : 1998 |
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Download Kraft Black Liquor Gasification and Direct Causticization with TiOŒ2 in a Fluidized Bed Book in PDF, ePub and Kindle
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Release | : 2009 |
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Download Causticizing for Black Liquor Gasifiers Book in PDF, ePub and Kindle
The cost-benefit outlook of black liquor gasification (BLG) could be greatly improved if the smelt causticization step could be achieved in situ during the gasification step. Or, at a minimum, the increase in causticizing load associated with BLG could be mitigated. A number of chemistries have been proven successful during black liquor combustion. In this project, three in situ causticizing processes (titanate, manganate, and borate) were evaluated under conditions suitable for high temperature entrained flow BLG, and low temperature steam reforming of black liquor. The evaluation included both thermodynamic modeling and lab experimentation. Titanate and manganate were tested for complete direct causticizing (to thus eliminate the lime cycle), and borates were evaluated for partial causticizing (to mitigate the load increase associated with BLG). Criteria included high carbonate conversion, corresponding hydroxide recovery upon hydrolysis, non process element (NPE) removal, and economics. Of the six cases (three chemistries at two BLG conditions), only two were found to be industrially viable: titanates for complete causticizing during high temperature BLG, and borates for partial causticizing during high temperature BLG. These two cases were evaluated for integration into a gasification-based recovery island. The Larsen [28] BLG cost-benefit study was used as a reference case for economic forecasting (i.e. a 1500 tpd pulp mill using BLG and upgrading the lime cycle). By comparison, using the titanate direct causticizing process yielded a net present value (NPV) of $25M over the NPV of BLG with conventional lime cycle. Using the existing lime cycle plus borate autocausticizing for extra capacity yielded a NPV of $16M.
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Release | : 2010 |
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Download Direct Causticizing for Black Liquor Gasification in a Circulating Fluidized Bed Book in PDF, ePub and Kindle
Gasification of black liquor (BLG) has distinct advantages over direct combustion in Tomlinson recovery boilers. In this project we seek to resolve causticizing issues in order to make pressurized BLG even more efficient and cost-effective. One advantage of BLG is that the inherent partial separation of sulfur and sodium during gasification lends itself to the use of proven high yield variants to conventional kraft pulping which require just such a separation. Processes such as polysulfide, split sulfidity, ASAQ, and MSSAQ can increase pulp yield from 1% to 10% over conventional kraft but require varying degrees of sulfur/sodium separation, which requires additional [and costly] processing in a conventional Tomlinson recovery process. However during gasification, the sulfur is partitioned between the gas and smelt phases, while the sodium all leaves in the smelt; thus creating the opportunity to produce sulfur-rich and sulfur-lean white liquors for specialty pulping processes. A second major incentive of BLG is the production of a combustible product gas, rich in H2 and CO. This product gas (a.k.a. "syngas") can be used in gas turbines for combined cycle power generation (which is twice as efficient as the steam cycle alone), or it can be used as a precursor to form liquid fuels, such as dimethyl ether or Fischer Tropsh diesel. There is drawback to BLG, which has the potential to become a third major incentive if this work is successful. The causticizing load is greater for gasification of black liquor than for combustion in a Tomlinson boiler. So implementing BLG in an existing mill would require costly increases to the causticizing capacity. In situ causticizing [within the gasifier] would handle the entire causticizing load and therefore eliminate the lime cycle entirely. Previous work by the author and others has shown that titanate direct causticizing (i.e. in situ) works quite well for high-temperature BLG (950°C), but was limited to pressures below about 5 bar. It is desirable however to operate BLG at 20-30 bar for efficiency reasons related to either firing the syngas in a turbine, or catalytically forming liquid fuels. This work focused on achieving high direct causticizing yields at 20 bars pressure. The titanate direct causticizing reactions are inhibited by CO2. Previous work has shown that the partial pressure of CO2 should be kept below about 0.5 bar in order for the process to work. This translates to a total reactor pressure limit of about 5 bar for airblown BLG, and only 2 bar for O2-blown BLG. In this work a process was developed in which the CO2 partial pressure could be manipulated to a level under 0.5 bar with the total system pressure at 10 bar during O2-blown BLG. This fell short of our 20 bar goal but still represents a substantial increase in the pressure limit. A material and energy balance was performed, as well as first-pass economics based on capital and utilities costs. Compared to a reference case of using BLG with a conventional lime cycle [Larson, 2003], the IRR and NVP were estimated for further replacing the lime kiln with direct causticizing. The economics are strongly dependent on the price of lime kiln fuel. At $6/mmBTU the lime cycle is the clear choice. At $8/mmBTU the NPV is $10M with IRR of 17%. At $12/mmBTU the NPV is $45M with IRR of 36%. To further increase the total allowable pressure, the CO2 could be further decreased by further decreasing the temperature. Testing should be done at 750C. Also a small pilot should be built.
Author | : Daniel Gershon |
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Total Pages | : 82 |
Release | : 2004 |
Genre | : Borates |
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Download Kinetics of Autocausticization Using Borates in a Black Liquor Gasification Process Book in PDF, ePub and Kindle
The path of research in the pulp and paper industry is heading towards the elimination of the lime cycle, which requires large amounts of energy, and changing the conventional recovery boiler system to a gasification process that will reduce the possibility of smelt water explosions while meeting future environmental regulations. Research has been carried out on both gasification processes and on causticizing processes that can replace or complement the lime cycle, however very little research has gone into the actual kinetics of causticization using black liquor in gasification processes. This research project fills in some of the missing knowledge in the area of kinetics of autocausticization reactions, which entails the use of borates as the autocausticizing agent. A temperature dependent kinetic model coupled with a mass transfer coefficient has been developed and compared to experimental data.