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NOVEL TECHNOLOGIES FOR GASEOUS CONTAMINANTS CONTROL

Description: Overall objective of this project was to develop a technology platform for cleaning/conditioning the syngas from an integrated gasification combined cycle (IGCC) system at elevated temperatures (500-1,000 F) and gasifier pressures to meet the tolerance limits for contaminants, including H{sub 2}S, COS, NH{sub 3}, HCl, Hg, and As. This technology development effort involved progressive development and testing of sorbent/catalytic materials and associated processes through laboratory, bench, pilot, and demonstration testing phases, coupled with a comprehensive systems analysis at various stages of development. The development of the regenerable RTI-3 desulfurization sorbent - a highly attrition-resistant, supported ZnO-based material - was the key discovery in this project. RTI-3's high attrition resistance, coupled with its high reactivity, effectively allowed its application in a high-velocity transport reactor system. Production of the RTI-3 sorbent was successfully scaled up to an 8,000-lb batch by Sued-Chemie. In October 2005, RTI obtained U.S Patent 6,951,635 to protect the RTI-3 sorbent technology and won the 2004 R&D 100 Award for development of this material. The RTI-3 sorbent formed the basis for the development of the High-Temperature Desulfurization System (HTDS), a dual-loop transport reactor system for removing the reduced sulfur species from syngas. An 83-foot-tall, pilot HTDS unit was constructed and commissioned first at ChevronTexaco's gasification site and later at Eastman's gasification plant. At Eastman, the HTDS technology was successfully operated with coal-derived syngas for a total of 3,017 hrs over a 12-month period and consistently reduced the sulfur level to <10 ppmv. The sorbent attrition rate averaged {approx}31 lb/MM lb of circulation. To complement the HTDS technology, which extracts the sulfur from syngas as SO{sub 2}, RTI developed the Direct Sulfur Recovery Process (DSRP). The DSRP, operating at high pressure and high temperature, uses a small slipstream of syngas to catalytically reduce the SO{sub 2} produced in the warm ...
Date: April 3, 2008
Creator: Turk, B. S.; Gupta, R. P.; Gangwal, S.; Toy, L. G.; Albritton, J. R.; Henningsen, G. et al.
Partner: UNT Libraries Government Documents Department

Integrated Warm Gas Multicontaminant Cleanup Technologies for Coal-Derived Syngas

Description: One of the key obstacles for the introduction of commercial gasification technology for the production of power with Integrated Gasification Combined Cycle (IGCC) plants or the production of value added chemicals, transportation fuels, and hydrogen has been the cost of these systems. This situation is particularly challenging because the United States has ample coal resources available as raw materials and effective use of these raw materials could help us meet our energy and transportation fuel needs while significantly reducing our need to import oil. One component of the cost of these systems that faces strong challenges for continuous improvement is removing the undesirable components present in the syngas. The need to limit the increase in cost of electricity to < 35% for new coal-based power plants which include CO{sub 2} capture and sequestration addresses both the growing social concern for global climate change resulting from the emission of greenhouse gas and in particular CO{sub 2} and the need to control cost increases to power production necessary to meet this social objective. Similar improvements to technologies for trace contaminants are getting similar pressure to reduce environmental emissions and reduce production costs for the syngas to enable production of chemicals from coal that is cost competitive with oil and natural gas. RTI, with DOE/NETL support, has been developing sorbent technologies that enable capture of trace contaminants and CO{sub 2} at temperatures above 400 °F that achieve better capture performance, lower costs and higher thermal efficiency. This report describes the specific work of sorbent development for mercury (Hg), arsenic (As), selenium (Se), cadmium (Cd), and phosphorous (P) and CO{sub 2} removal. Because the typical concentrations of Hg, As, Se, Cd, and P are less than 10 ppmv, the focus has been on single-use sorbents with sufficient capacity to ensure replacement costs are cost ...
Date: September 30, 2010
Creator: Turk, Brian; Gupta, Raghubir; Sharma, Pradeepkumar; Albritton, Johnny & Jamal, Aqil
Partner: UNT Libraries Government Documents Department

Determination of the Effect of Coal/Biomass-Derived Syngas Contaminants on the Performance of Fischer-Tropsch and Water-Gas-Shift Catalysts

Description: Today, nearly all liquid fuels and commodity chemicals are produced from non-renewable resources such as crude oil and natural gas. Because of increasing scrutiny of carbon dioxide (CO{sub 2}) emissions produced using traditional fossil-fuel resources, the utilization of alternative feedstocks for the production of power, hydrogen, value-added chemicals, and high-quality hydrocarbon fuels such as diesel and substitute natural gas (SNG) is critical to meeting the rapidly growing energy needs of modern society. Coal and biomass are particularly attractive as alternative feedstocks because of the abundant reserves of these resources worldwide. The strategy of co-gasification of coal/biomass (CB) mixtures to produce syngas for synthesis of Fischer-Tropsch (FT) fuels offers distinct advantages over gasification of either coal or biomass alone. Co-feeding coal with biomass offers the opportunity to exploit economies of scale that are difficult to achieve in biomass gasification, while the addition of biomass to the coal gasifier feed leverages proven coal gasification technology and allows CO{sub 2} credit benefits. Syngas generated from CB mixtures will have a unique contaminant composition because coal and biomass possess different concentrations and types of contaminants, and the final syngas composition is also strongly influenced by the gasification technology used. Syngas cleanup for gasification of CB mixtures will need to address this unique contaminant composition to support downstream processing and equipment. To investigate the impact of CB gasification on the production of transportation fuels by FT synthesis, RTI International conducted thermodynamic studies to identify trace contaminants that will react with water-gas-shift and FT catalysts and built several automated microreactor systems to investigate the effect of single components and the synergistic effects of multiple contaminants on water-gas-shift and FT catalyst performance. The contaminants investigated were sodium chloride (NaCl), potassium chloride (KCl), hydrogen sulfide (H{sub 2}S), carbonyl sulfide (COS), ammonia (NH{sub 3}), and combinations thereof. This report ...
Date: December 31, 2010
Creator: Trembly, Jason; Cooper, Matthew; Farmer, Justin; Turk, Brian & Gupta, Raghubir
Partner: UNT Libraries Government Documents Department

Carbon Dioxide Capture from Flue Gas Using Dry, Regenerable Sorbents

Description: This report describes research conducted between January 1, 2006, and March 31, 2006, on the use of dry regenerable sorbents for removal of carbon dioxide (CO{sub 2}) from coal combustion flue gas. An integrated system composed of a downflow co-current contact absorber and two hollow screw conveyors (regenerator and cooler) was assembled, instrumented, debugged, and calibrated. A new batch of supported sorbent containing 15% sodium carbonate was prepared and subjected to surface area and compact bulk density determination.
Date: March 31, 2006
Creator: Green, David A.; Nelson, Thomas O.; Turk, Brian S.; Box, Paul D. & Gupta, Raghubir P.
Partner: UNT Libraries Government Documents Department

Carbon Dioxide Capture from Flue Gas Using Dry, Regenerable Sorbents

Description: This report describes research conducted between July 1, 2006 and September 30, 2006 on the use of dry regenerable sorbents for removal of carbon dioxide (CO{sub 2}) from coal combustion flue gas. Modifications to the integrated absorber/ sorbent regenerator/ sorbent cooler system were made to improve sorbent flow consistency and measurement reliability. Operation of the screw conveyor regenerator to achieve a sorbent temperature of at least 120 C at the regenerator outlet is necessary for satisfactory carbon dioxide capture efficiencies in succeeding absorption cycles. Carbon dioxide capture economics in new power plants can be improved by incorporating increased capacity boilers, efficient flue gas desulfurization systems and provisions for withdrawal of sorbent regeneration steam in the design.
Date: September 30, 2006
Creator: Green, David A.; Nelson, Thomas O.; Turk, Brian S. & Gupta, Paul D. Box Raghubir P.
Partner: UNT Libraries Government Documents Department

Carbon Dioxide Capture from Flue Gas Using Dry Regenerable Sorbents

Description: Regenerable sorbents based on sodium carbonate (Na{sub 2}CO{sub 3}) can be used to separate carbon dioxide (CO{sub 2}) from coal-fired power plant flue gas. Upon thermal regeneration and condensation of water vapor, CO{sub 2} is released in a concentrated form that is suitable for reuse or sequestration. During the research project described in this report, the technical feasibility and economic viability of a thermal-swing CO{sub 2} separation process based on dry, regenerable, carbonate sorbents was confirmed. This process was designated as RTI's Dry Carbonate Process. RTI tested the Dry Carbonate Process through various research phases including thermogravimetric analysis (TGA); bench-scale fixed-bed, bench-scale fluidized-bed, bench-scale co-current downflow reactor testing; pilot-scale entrained-bed testing; and bench-scale demonstration testing with actual coal-fired flue gas. All phases of testing showed the feasibility of the process to capture greater than 90% of the CO{sub 2} present in coal-fired flue gas. Attrition-resistant sorbents were developed, and these sorbents were found to retain their CO{sub 2} removal activity through multiple cycles of adsorption and regeneration. The sodium carbonate-based sorbents developed by RTI react with CO{sub 2} and water vapor at temperatures below 80 C to form sodium bicarbonate (NaHCO3) and/or Wegscheider's salt. This reaction is reversed at temperatures greater than 120 C to release an equimolar mixture of CO{sub 2} and water vapor. After condensation of the water, a pure CO{sub 2} stream can be obtained. TGA testing showed that the Na{sub 2}CO3 sorbents react irreversibly with sulfur dioxide (SO{sub 2}) and hydrogen chloride (HCl) (at the operating conditions for this process). Trace levels of these contaminants are expected to be present in desulfurized flue gas. The sorbents did not collect detectable quantities of mercury (Hg). A process was designed for the Na{sub 2}CO{sub 3}-based sorbent that includes a co-current downflow reactor system for adsorption of CO{sub 2} ...
Date: June 30, 2007
Creator: Nelson, Thomas; Green, David; Box, Paul; Gupta, Raghubir & Henningsen, Gennar
Partner: UNT Libraries Government Documents Department

Carbon Dioxide Capture from Flue Gas Using Dry Regenerable Sorbents

Description: Laboratory studies were conducted to investigate dry, regenerable, alkali carbonate-based sorbents for the capture of CO{sub 2} from power plant flue gas. Electrobalance, fixed-bed and fluid-bed reactors were used to examine both the CO{sub 2} capture and sorbent regeneration phases of the process. Sodium carbonate-based sorbents (calcined sodium bicarbonate and calcined trona) were the primary focus of the testing. Supported sodium carbonate and potassium carbonate sorbents were also tested. Sodium carbonate reacts with CO{sub 2} and water vapor contained in flue gas at temperatures between 60 and 80 C to form sodium bicarbonate, or an intermediate salt (Wegscheider's salt). Thermal regeneration of this sorbent produces an off-gas containing equal molar quantities of CO{sub 2} and H{sub 2}O. The low temperature range in which the carbonation reaction takes place is suited to treatment of coal-derived flue gases following wet flue gas desulfurization processes, but limits the concentration of water vapor which is an essential reactant in the carbonation reaction. Sorbent regeneration in an atmosphere of CO{sub 2} and water vapor can be carried out at a temperature of 160 C or higher. Pure CO{sub 2} suitable for use or sequestration is available after condensation of the H{sub 2}O. Flue gas contaminants such as SO{sub 2} react irreversibly with the sorbent so that upstream desulfurization will be required when sulfur-containing fossil fuels are used. Approximately 90% CO{sub 2} capture from a simulated flue gas was achieved during the early stages of fixed-bed reactor tests using a nominal carbonation temperature of 60 C. Effectively complete sorbent carbonation is possible when the fixed-bed test is carried out to completion. No decrease in sorbent activity was noted in a 15-cycle test using the above carbonation conditions coupled with regeneration in pure CO{sub 2} at 160 C. Fluidized-bed reactor tests of up to five cycles were ...
Date: September 30, 2004
Creator: Green, David A.; Turk, Brian S.; Portzer, Jeffrey W.; Gupta, Raghubir P.; McMichael, William J.; Nelson, Thomas et al.
Partner: UNT Libraries Government Documents Department

Carbon Dioxide Capture from Flue Gas Using Dry, Regenerable Sorbents

Description: This report describes research conducted between July 1, 2005, and September 30, 2005, on the use of dry regenerable sorbents for removal of carbon dioxide (CO{sub 2}) from flue gas from coal combustion. A new batch of supported sorbent containing 10% sodium carbonate (Na{sub 2}CO{sub 3}) was obtained and characterized. Thermogravimetric analysis (TGA) testing confirmed that the Na{sub 2}CO{sub 3} sorbent reacted with sulfur dioxide (SO{sub 2}) at temperatures between 40 and 160 C. Although the rate of reaction was more rapid at lower temperatures, these data suggest that SO{sub 2} will not be released from the sorbent under expected sorbent-regeneration conditions. Preliminary work has been conducted to establish the design specifications for a laboratory screw-conveyor sorbent regeneration/cooling apparatus. A plan for a scheduled pilot-scale test of a heated hollow-screw conveyor was developed. This test will be conducted at facilities of the screw conveyor fabricator. This test will confirm the extent of sorbent regeneration and will provide data to evaluate multi-cycle sorbent attrition rates associated with this type of processing.
Date: October 1, 2005
Creator: Green, David A.; Nelson, Thomas; Turk, Brian S.; Box, Paul & Gupta, Raghubir P.
Partner: UNT Libraries Government Documents Department

Carbon Dioxide Capture from Flue Gas Using Dry, Regenerable Sorbents

Description: This report describes research conducted between October 1, 2005, and December 31, 2005, on the use of dry regenerable sorbents for removal of carbon dioxide (CO{sub 2}) from flue gas from coal combustion. A field test was conducted to examine the extent to which RTI's supported sorbent can be regenerated in a heated, hollow screw conveyor. This field test was conducted at the facilities of a screw conveyor manufacturer. The sorbent was essentially completely regenerated during this test, as confirmed by thermal desorption and mass spectroscopy analysis of the regenerated sorbent. Little or no sorbent attrition was observed during 24 passes through the heated screw conveyor system. Three downflow contactor absorption tests were conducted using calcined sodium bicarbonate as the absorbent. Maximum carbon dioxide removals of 57 and 91% from simulated flue gas were observed at near ambient temperatures with water-saturated gas. These tests demonstrated that calcined sodium carbonate is not as effective at removing CO{sub 2} as are supported sorbents containing 10 to 15% sodium carbonate. Delivery of the hollow screw conveyor for the laboratory-scale sorbent regeneration system was delayed; however, construction of other components of this system continued during the quarter.
Date: January 1, 2006
Creator: Green, David A.; Nelson, Thomas O.; Turk, Brian S.; Box, Paul D.; Weber, Andreas & Gupta, Raghubir P.
Partner: UNT Libraries Government Documents Department

Co-Production of Electricity and Hydrogen Using a Novel Iron-based Catalyst

Description: The primary objective of this project was to develop a hydrogen production technology for gasification applications based on a circulating fluid-bed reactor and an attrition resistant iron catalyst. The work towards achieving this objective consisted of three key activities: • Development of an iron-based catalyst suitable for a circulating fluid-bed reactor • Design, construction, and operation of a bench-scale circulating fluid-bed reactor system for hydrogen production • Techno-economic analysis of the steam-iron and the pressure swing adsorption hydrogen production processes. This report describes the work completed in each of these activities during this project. The catalyst development and testing program prepared and iron-based catalysts using different support and promoters to identify catalysts that had sufficient activity for cyclic reduction with syngas and steam oxidation and attrition resistance to enable use in a circulating fluid-bed reactor system. The best performing catalyst from this catalyst development program was produced by a commercial catalyst toll manufacturer to support the bench-scale testing activities. The reactor testing systems used during material development evaluated catalysts in a single fluid-bed reactor by cycling between reduction with syngas and oxidation with steam. The prototype SIP reactor system (PSRS) consisted of two circulating fluid-bed reactors with the iron catalyst being transferred between the two reactors. This design enabled demonstration of the technical feasibility of the combination of the circulating fluid-bed reactor system and the iron-based catalyst for commercial hydrogen production. The specific activities associated with this bench-scale circulating fluid-bed reactor systems that were completed in this project included design, construction, commissioning, and operation. The experimental portion of this project focused on technical demonstration of the performance of an iron-based catalyst and a circulating fluid-bed reactor system for hydrogen production. Although a technology can be technically feasible, successful commercial deployment also requires that a technology offer an economic advantage over ...
Date: September 30, 2011
Creator: Hilaly, Ahmad; Georgas, Adam; Leboreiro, Jose; Arora, Salil; Head, Megann; Trembly, Jason et al.
Partner: UNT Libraries Government Documents Department

CO{sub 2} Reuse in Petrochemical Facilities

Description: To address public concerns regarding the consequences of climate change from anthropogenic carbon dioxide (CO{sub 2}) emissions, the U.S. Department of Energy's National Energy Technology Laboratory (DOE/NETL) is actively funding a CO{sub 2} management program to develop technologies capable of mitigating CO{sub 2} emissions from power plant and industrial facilities. Over the past decade, this program has focused on reducing the costs of carbon capture and storage technologies. Recently, DOE/NETL launched an alternative CO{sub 2} mitigation program focused on beneficial CO{sub 2} reuse to support the development of technologies that mitigate emissions by converting CO{sub 2} into valuable chemicals and fuels. RTI, with DOE/NETL support, has been developing an innovative beneficial CO{sub 2} reuse process for converting CO{sub 2} into substitute natural gas (SNG) by using by-product hydrogen (H{sub 2)-containing fuel gas from petrochemical facilities. This process leveraged commercial reactor technology currently used in fluid catalytic crackers in petroleum refining and a novel nickel (Ni)-based catalyst developed by RTI. The goal was to generate an SNG product that meets the pipeline specifications for natural gas, making the SNG product completely compatible with the existing natural gas infrastructure. RTI's technology development efforts focused on demonstrating the technical feasibility of this novel CO{sub 2} reuse process and obtaining the necessary engineering information to design a pilot demonstration unit for converting about 4 tons per day (tons/day) of CO{sub 2} into SNG at a suitable host site. This final report describes the results of the Phase I catalyst and process development efforts. The methanation activity of several commercial fixed-bed catalysts was evaluated under fluidized-bed conditions in a bench-scale reactor to identify catalyst performance targets. RTI developed two fluidizable Ni-based catalyst formulations (Cat-1 and Cat-3) that demonstrated equal or better performance than that of commercial methanation catalysts. The Cat-1 and Cat-3 formulations were successfully ...
Date: December 31, 2010
Creator: Trembly, Jason; Turk, Brian; Pavani, Maruthi; McCarty, Jon; Boggs, Chris; Jamal, Aqil et al.
Partner: UNT Libraries Government Documents Department

CO{sub 2} Capture Membrane Process for Power Plant Flue Gas

Description: Because the fleet of coal-fired power plants is of such importance to the nation’s energy production while also being the single largest emitter of CO{sub 2}, the development of retrofit, post-combustion CO{sub 2} capture technologies for existing and new, upcoming coal power plants will allow coal to remain a major component of the U.S. energy mix while mitigating global warming. Post-combustion carbon capture technologies are an attractive option for coal-fired power plants as they do not require modification of major power-plant infrastructures, such as fuel processing, boiler, and steam-turbine subsystems. In this project, the overall objective was to develop an advanced, hollow-fiber, polymeric membrane process that could be cost-effectively retrofitted into current pulverized coal-fired power plants to capture at least 90% of the CO{sub 2} from plant flue gas with 95% captured CO{sub 2} purity. The approach for this project tackled the technology development on three different fronts in parallel: membrane materials R&D, hollow-fiber membrane module development, and process development and engineering. The project team consisted of RTI (prime) and two industrial partners, Arkema, Inc. and Generon IGS, Inc. Two CO{sub 2}-selective membrane polymer platforms were targeted for development in this project. For the near term, a next-generation, high-flux polycarbonate membrane platform was spun into hollow-fiber membranes that were fabricated into both lab-scale and larger prototype (~2,200 ft{sup 2}) membrane modules. For the long term, a new fluoropolymer membrane platform based on poly(vinylidene fluoride) [PVDF] chemistry was developed using a copolymer approach as improved capture membrane materials with superior chemical resistance to flue-gas contaminants (moisture, SO{sub 2}, NOx, etc.). Specific objectives were:  Development of new, highly chemically resistant, fluorinated polymers as membrane materials with minimum selectivity of 30 for CO{sub 2} over N{sub 2} and CO{sub 2} permeance greater than 300 gas permeation units (GPU) targeted;  Development of ...
Date: September 30, 2011
Creator: Toy, Lora; Kataria, Atish & Gupta, Raghubir
Partner: UNT Libraries Government Documents Department

The Development of a Robust Accelerometer-Based Start of Combustion Sensing System

Description: Polymer nanofibers are nanoscale materials whose properties can be adjusted to provide desirable light management performance for high efficiency solid-state lighting luminaires. The polymeric nanofibers at the core of this project have diameters on the order of 100 to 1000 nm and a length of more than 1 cm. By controlling fiber diameter, fiber packing, and fiber morphology, a low cost, high performance optical material can be fabricated. This report describes the fabrication of these nanofiber structures and their uses and benefits in solid-state lighting application. When used in solid state lighting devices, nanofibers can take the form of either diffuse reflectors or photoluminescent materials. Nanofiber reflectors (NFR) were developed which displayed high diffuse reflectance with reflectance values in excess of 0.90. In contrast, traditional reflector materials such as aluminum and paint typically possess reflectance values below 0.80 and absorb a larger fraction of light, reducing luminaire output efficiency. The incorporation of the NFR technology into reflectors, troffers, and beam formers present in SSL luminaires provides better reflectance and lower light loss than is possible with conventional materials. Photoluminescent nanofibers (PLN) can be formed by combining nanofibers with photoluminescent materials such as phosphors and quantum dots (QD). Forming the PLN with the proper combination of green and red luminescent materials and exciting the nanocomposite with a blue light emitting diode (LED) has been demonstrated to produce high efficiency (&gt; 55 lumens per watt) white light with excellent color rendering properties. The incorporation of QDs in the PLN is particularly advantageous in that this approach enables the correction of any color deficiencies in the light source without creating unnecessary radiation in the near infrared. Cost models developed during this project have demonstrated that both the NFR and PLN materials can be mass produced at a manufacturing cost of less than $5 ...
Date: March 31, 2010
Creator: Davis, Lynn
Partner: UNT Libraries Government Documents Department

CARBON DIOXIDE CAPTURE FROM FLUE GAS USING DRY REGENERABLE SORBENTS

Description: This report describes research conducted between April 1, 2005 and June 30, 2005 on the use of dry regenerable sorbents for removal of carbon dioxide from flue gas from coal combustion and synthesis gas from coal gasification. Supported sodium carbonate sorbents removed up to 76% of the carbon dioxide from simulated flue gas in a downflow cocurrent flow reactor system, with an approximate 15 second gas-solid contact time. This reaction proceeds at temperatures as low as 25 C. Lithium silicate sorbents remove carbon dioxide from high temperature simulated flue gas and simulated synthesis gas. Both sorbent types can be thermally regenerated and reused. The lithium silicate sorbent was tested in a thermogravimetric analyzer and in a 1-in quartz reactor at atmospheric pressure; tests were also conducted at elevated pressure in a 2-in diameter high temperature high pressure reactor system. The lithium sorbent reacts rapidly with carbon dioxide in flue gas at 350-500 C to absorb about 10% of the sorbent weight, then continues to react at a lower rate. The sorbent can be essentially completely regenerated at temperatures above 600 C and reused. In atmospheric pressure tests with synthesis gas of 10% initial carbon dioxide content, the sorbent removed over 90% of the carbon dioxide. An economic analysis of a downflow absorption process for removal of carbon dioxide from flue gas with a supported sodium carbonate sorbent suggests that a 90% efficient carbon dioxide capture system installed at a 500 MW{sub e} generating plant would have an incremental capital cost of $35 million ($91/kWe, assuming 20 percent for contingencies) and an operating cost of $0.0046/kWh. Assuming capital costs of $1,000/kW for a 500 MWe plant the capital cost of the down flow absorption process represents a less than 10% increase, thus meeting DOE goals as set forth in its Carbon ...
Date: July 1, 2005
Creator: Green, David A.; Nelson, Thomas; Turk, Brian S.; Box, Paul; Li, Weijiong & Gupta, Raghubir P.
Partner: UNT Libraries Government Documents Department

A novel carbon-based process for flue-gas cleanup. Final report

Description: A low-temperature process employing activated carbon-based catalysts and operating downstream of the electrostatic precipitator (ESP) was evaluated jointly by Research Triangle Institute (RTI) and the University of Waterloo (Waterloo). The RTI-Waterloo process was projected to be capable of removing more than 95% SO{sub 2} and 75% NO{sub x }from coal combustion flue gas. In the process, the flue gas leaving the ESP is first cooled to approximately 100{degree}C. The SO{sub 2} is then catalytically oxidized to SO{sub 3} which is removed as medium-strength sulfuric acid in a series of periodically flushed trickle-bed reactors containing an activated carbon-based catalyst. The SO{sub 2}-free gas is then reheated to approximately 150{degree}C and NH{sub 3} is injected into the gas stream. It is then passed over a fixed bed of another activated carbon-based catalyst to reduce the NO{sub x} to N{sub 2} and H{sub 2}O. The clean flue gas is then vented to the stack. The feasibility of the process has been demonstrated in laboratory-scale experiments using simulated flue gas. Catalysts have been identified that gave the required performance for SO{sub 2} and NO{sub x} removal with <25 ppM NH{sub 3} slip. Potential for producing up to 10 N sulfuric acid by periodically flushing the SO{sub 2} removal reactor and further concentration to industrial strength 93.17% sulfuric acid was also demonstrated. Using the results of the experimental work, an engineering evaluation was conducted. Cost for the RTI-Waterloo process was competitive with conventional selective catalytic reduction (SCR) -- flue gas desulfurization (FGD) process and other emerging combined SO{sub 2}/NO{sub x} removal processes.
Date: October 1, 1993
Creator: Gangwal, S. K.; Howe, G. B.; McMichael, W. J. & Spivey, J. J.
Partner: UNT Libraries Government Documents Department

Bench-scale demonstration of hot-gas desulfurization technology. Quarterly technical progress report, July 1, 1993--September 30, 1993

Description: The US Department of Energy (DOE), Morgantown Energy Technology Center (METC), is sponsoring research in advanced methods for controlling contaminants in hot coal gasifier gas (coal gas) streams of integrated gasification combined-cycle (IGCC) power systems. The programs focus on hot-gas particulate removal and desulfurization technologies that match or nearly match the temperatures and pressures of the gasifier, cleanup system, and power generator. The purpose is to eliminate the need for expensive heat recovery equipment, reduce efficiency losses due to quenching, and minimize wastewater treatment costs. Hot-gas desulfurization research has focused on regenerable mixed-metal oxide sorbents which can reduce the sulfur in coal gas to less than 20 ppmv and can be regenerated in a cyclic manner with air for multicycle operation. Zinc titanate (Zn{sub 2}TiO{sub 4} or ZnTiO{sub 3}), formed by a solid-state reaction of zinc oxide (ZnO) and titanium dioxide (TiO{sub 2}), is currently the leading sorbent. The sulfidation/regeneration cycle can be carried out in fixed-bed, moving-bed, or fluidized-bed reactor configuration, and all three types of reactors are slated for demonstration in the DOE Clean Coal Technology program. The fluidized-bed reactor configuration is most attractive because of several potential advantages including faster kinetics and the ability to handle the highly exothermic regeneration to produce a regeneration offgas containing a constant concentration of SO{sub 2}.
Date: December 31, 1993
Partner: UNT Libraries Government Documents Department

Catalytic carbon membranes for hydrogen production. Final report

Description: Commercial carbon composite microfiltration membranes may be modified for gas separation applications by providing a gas separation layer with pores in the 1- to 10-nm range. Several organic polymeric precursors and techniques for depositing a suitable layer were investigated in this project. The in situ polymerization technique was found to be the most promising, and pure component permeation tests with membrane samples prepared with this technique indicated Knudsen diffusion behavior. The gas separation factors obtained by mixed-gas permeation tests were found to depend strongly on gas temperature and pressure indicating significant viscous flow at high-pressure conditions. The modified membranes were used to carry out simultaneous water gas shift reaction and product hydrogen separation. These tests indicated increasing CO conversions with increasing hydrogen separation. A simple process model was developed to simulate a catalytic membrane reactor. A number of simulations were carried out to identify operating conditions leading to product hydrogen concentrations over 90 percent. (VC)
Date: January 1, 1992
Creator: Damle, A. S. & Gangwal, S. K.
Partner: UNT Libraries Government Documents Department

Enhanced durability of high-temperature desulfurization sorbents for fluidized-bed applications

Description: The objectives of this project are to identify and demonstrate methods for enhancing long-term chemical reactivity and attrition resistance of zinc ferrite and zinc titanate sorbents to be employed for desulfurization of hot coal-derived gases in a high-temperature, high-pressure (HTHP) fluid-bed reactor. The sorbent formulation specified for study during the base period of this project was zinc ferrite. Zinc titanate sorbents are being studied under two options to the base contract. Specific objectives of the zinc titanate sorbent development work are the following: The effect of following process variables was investigated o the performance of zinc titanate sorbents: Method of sorbent preparation, Composition of fuel gas, Zn to Ti ratio of the sorbent, Sulfidation temperature, and Superficial gas velocity. The effect of first three variables has been covered in RTI`s 1991 paper (Gupta and Gangwal, 1991b), while the effect of temperature and superficial gas velocity is described here.
Date: November 1, 1992
Creator: Gupta, R. P. & Gangwal, S. K.
Partner: UNT Libraries Government Documents Department

A novel carbon-based process for flue gas cleanup. Third quarterly technical progress report, January 1--March 31, 1992

Description: The objective of this project is to demonstrate the preliminary technical and economic feasibility of a novel carbon-based process for removal of at least 95% SO{sub 2} and at least 75% NO{sub x} coal combustion flue gas. In the process, flue gas leaving the electrostatic precipitator (ESP) is passed through a trickle bed of achieved carbon catalyst employing a periodic flush of low strength sulfuric acid. The SO{sub 2} is oxidized to SO{sub 3} and removed as medium strength sulfuric acid. The SO{sub 2}-free flue gas is then mixed with NH{sub 3}, and the NO{sub x} in the gas is subjected to selective catalytic reduction (SCR) to N{sub 2} over a fixed bed of activated carbon catalyst. The experimental work is divided between Research Triangle Institute (RTI) and the University of Waterloo (Waterloo). RTI will conduct the NO{sub x} removal studies, whereas Waterloo will conduct the SO{sub 2} removal studies. The ultimate goal of the project is to demonstrate that the process can be reduce the cost of electricity by 20% over conventional SCR/flue gas desulfurization (FGD) processes. In the present quarter, the continuous SO{sub 2} analyzer system at Waterloo was completed. The SO{sub 2} removal factorial experiments were begun Waterloo with the BPL carbon at 21{degrees}C. Also, SO{sub 2} removal was tested on two catalyst at RTI at 80{degrees}C. NO{sub x} conversion was tested on a variety of catalysts at RTI. It was shown that the BPL carbon could remove over 95% SO{sub 2} at 21{degrees}C but would required several beds at space velocity in each bed of abut 1,500 scc/(cc{center_dot}h) to reduce SO{sub 2} from 2,500 ppm to 100 ppm. A modified carbon catalyst tested at RTI showed 99% SO{sub 2} removal at 80{degrees}C at 1,400 scc/(cc{center_dot}h). Also, it was possible to produce nearly 9 normal H{sub 2}SO{sub ...
Date: April 1, 1992
Creator: Gangwal, S. K. & Silveston, P. L.
Partner: UNT Libraries Government Documents Department

Sulfur recovery from low-quality natural gas

Description: The objectives of this work are to (1) demonstrate on a bench-scale the Direct Sulfur Recovery Process (DSRP) for up to 99% or higher recovery of sulfur (as elemental sulfur) from SO{sub 2}-containing regeneration off-gases produced in integrated gasification combined cycle (IGCC) power generating systems employing hot-gas cleanup and (2) promote DSRP technology transfer to industry. The treatment of SO{sub 2}-containing regeneration off-previously (Gangwal and McMichael, 1991). Technology transfer activities have involved meetings with several industrial organizations, presentations at national scientific conferences, and experiments to evaluate DSRP`s potential for treating various H{sub 2}S-containing gases such as low-quality natural gas (LQNG) and amine regeneration gas. This paper will discuss the results of DSRP experiments with H{sub 2}S-containing gases.
Date: June 1, 1992
Creator: Ganwal, S. K. & McMichael, W. J.
Partner: UNT Libraries Government Documents Department

High-temperature, high-pressure testing of zinc titanate in a bench-scale fluidized-bed reactor for 100 cycles

Description: Integrated gasification combined cycle (IGCC) power plants are being advanced worldwide to produce electricity from coal owing to their potential for superior environmental performance, economics, and efficiency in comparison to conventional coal-based power plants. A key component of these plants is a hot-gas desulfurization system employing efficient regenerable mixed-metal oxide sorbents. Leading sorbent candidates include zinc ferrite and zinc titanate. These sorbents can remove hydrogen sulfide (H{sub 2}S) in the fuel gas down to very low levels (typically <20 ppmv) at 500 to 750{degree}C and can be readily regenerated for multicycle operation with air. To this end, the Research Triangle Institute (RTI) has formulated and tested a series of zinc titanate sorbents in a high-temperature, high- pressure HTHP fluidized-bed bench-scale reactor. Multicycle HTHP bench-scale testing of these sorbents under a variety of conditions culminated in the development of a ZT-4 sorbent that exhibited the best overall performance in terms of chemical reactivity, sulfur capacity, regenerability, structural properties, and attrition resistance. Following this parametric study, a life-cycle test consisting of 100 sulfidation-regeneration cycles was carried out with ZT-4 in the bench unit.
Date: June 1, 1993
Creator: Gupta, R. P. & Gangwal, S. K.
Partner: UNT Libraries Government Documents Department

Enhanced durability of desulfurization sorbents for fluidized-bed applications

Description: Advanced integrated gasification combined cycle (IGCC) power systems require the development of high-temperature desulfurization sorbents capable of removing hydrogen sulfide from coal gasifier down to very low levels. The objective of this investigation was to identify and demonstrate methods for enhancing the long-term chemical reactivity and mechanical strength of zinc ferrite, a leading regenerable sorbent, for fluidized-bed applications. Fluidized sorbent beds offer significant potential in IGCC systems because of their ability to control the highly exothermic regeneration involved. However, fluidized beds require a durable, attrition-resistant sorbent in the 100--300 {mu}m size range. A bench-scale high-temperature, high- pressure (HTHP) fluidized-bed reactor (7.6-cm I.D.) system capable of operating up to 24 atm and 800{degree}C was designed, built and tested. A total of 175 sulfidation-regeneration cycles were carried out using KRW-type coal gas with various zinc ferrite formulations. A number of sorbent manufacturing techniques including spray drying, impregnation, crushing and screening, and granulation were investigated. While fluidizable sorbents prepared by crushing durable pellets and screening had acceptable sulfur capacity, they underwent excessive attrition during multicycle testing. The sorbent formulations prepared by a proprietary technique were found to have excellent attrition resistance and acceptable chemical reactivity during multicycle testing. However, zinc ferrite was found to be limited to 550{degree}C, beyond which excessive sorbent weakening due to chemical transformations, e.g., iron oxide reduction, was observed.
Date: June 1, 1991
Creator: Gupta, R. P. & Gangwal, S. K.
Partner: UNT Libraries Government Documents Department

Bench-scale demonstration of hot-gas desulfurization technology. Quarterly technical progress report, October 1--December 31, 1993

Description: Research Triangle Institute (RTI) with DOE/METC sponsorship has been developing zinc titanate sorbent technology since 1986. In addition, RTI has been developing the Direct Sulfur Recovery Process (DSRP) with DOE/METC sponsorship since 1988. Fluidized-bed zinc titanate desulfurization coupled to the DSRP is currently the most advanced and attractive technology for sulfur removal/recovery for IGCC systems, and it has recently been proposed in a Clean Coal Technology project. The goal of this project is to continue further development of the zinc titanate desulfurization and DSRP technologies by: scaling up the zinc titanate reactor system; developing an integrated skid-mounted zinc titanate desulfurization-DSRP reactor system; testing the integrated system over an extended period with real coal-gas from an operating gasifier to quantify the degradative effect, if any, of the trace contaminants present in coal gas; developing an engineering database suitable for system scaleup; and designing, fabricating and commissioning a larger DSRP reactor system capable of operating on a six-fold greater volume of gas than the DSRP reactor used in the bench-scale field test. During this reporting period the Construction Permit Application was completed and approved by the Process Safety Committee, and a final revised Application has been submitted to DOE/METC. A draft Test Plan for the field test was formulated. Finally, progress was made in the reactor system fabrication with the submission of purchase orders for nearly all major equipment, and with the final design of the trailer (mobile laboratory).
Date: April 1, 1994
Partner: UNT Libraries Government Documents Department

Bench-scale testing and evaluation of the Direct Sulfur Recovery Process

Description: The present work seeks to (1) demonstrate the DSRP in an integrated two-stage bench-scale unit scaled up by a factor of up to 40, for up to 99 percent or higher recovery of sulfur, (2) explain the high sulfur yield and mechanism of DSRP reactions by conducting kinetic experiments and advanced thermodynamic calculations, and (3) continue technology transfer to the point where industry is willing to support further DSRP development. The DSRP Bench-Scale Unit hardware has been described in detail previously (Gangwal and McMichael, 1990; Gangwal and McMichael, 1991). The unit consists of a simulated off-gas and coal-gas delivery system connected to two high-pressure reactors and condensers in the configuration shown conceptually in Figure 1. The system is rated to 400 psig and the reactors, capable of operation at up to 400 psig at 750{degree}C, hold up to 1 L of catalyst each. The inlet and outlet gases are analyzed using two gas chromatographs (GCs) and a continuous SO{sub 2} analyzer. One major change recently made to the unit consists of installing advanced condensers suggested by experts in the field to facilitate more efficient separation of the sulfur after each reactor. A schematic diagram of the advanced condenser is shown in Figure 2. The sulfur-laden gas is cooled by surrounding steam at 250{degree}F in a coil and then flashed into the sulfur collection pot for separation of gas and sulfur. A sulfur drain is included so that it is not necessary to dismantle the condenser after every run. The ability to drain the sulfur during a run allows extended runs to be carried out. Also fittings are provided in strategic locations to allow dismantling when cleanup becomes necessary.
Date: November 1, 1992
Creator: Gangwal, S. K.; McMichael, W. J.; Agarwal, S. K.; Chen, D. H. & Hopper, J. R.
Partner: UNT Libraries Government Documents Department