Low-emission Boiler Systems Research Articles

Towards Ideal NOx and CO2 Emission Control Technology for Bio-Oils Combustion Energy System Using a Plasma-Chemical Hybrid Process

A pilot-scale low-emission boiler system consisting of a bio-fuel boiler and plasma-chemical hybrid NOx removal system is investigated. This system can achieve carbon neutrality because the bio-fuel boiler uses waste vegetable oil as one of the fuels. The plasma-chemical hybrid NOx removal system has two processes: NO oxidation by ozone produced from plasma ozonizers and NO2 removal using a Na2SO3 chemical scrubber. Test demonstrations of the system are carried out for mixed oils (mixture of A-heavy oil and waste vegetable oil). Stable combustion is achieved for the mixed oil (20 – 50% waste vegetable oil). Properties of flue gas—e.g., O2, CO2 and NOx—when firing mixed oils are nearly the same as those when firing heavy oil for an average flue gas flow rate of 1000 Nm3/h. NOx concentrations at the boiler outlet are 90 – 95 ppm. Furthermore, during a 300-min continuous operation when firing 20% mixed oil, NOx removal efficiency of more than 90% (less than 10 ppm NOx emission) is confirmed. In addition, the CO2 reduction when heavy oil is replaced with waste vegetable oil is estimated. The system comparison is described between the plasma-chemical hybrid NOx removal and the conventional technology.

Development of Low-Emission Bio-Fuel Boiler System With Plasma-Chemical Hybrid $\hbox{NO}_{\rm x}$ Reduction

A pilot-scale low-emission boiler system consisting of a bio-fuel boiler and a plasma-chemical hybrid NOx removal system is investigated. This system can achieve carbon neutrality because the bio-fuel boiler uses waste vegetable oil (WVO) as one of the fuels. The plasma-chemical hybrid NOx removal system has two processes: NO oxidation by ozone produced from plasma ozonizers and NO2 removal using a Na2SO3 chemical scrubber. Test demonstrations of the system were carried out for mixed oils (mixture of heavy oil and WVO). A stable combustion was achieved for the mixed oil (20%-50% WVO). The properties of flue gas-e.g., O2, CO2, and NOx -when firing mixed oils were nearly the same as those when firing heavy oil for an average flue gas flow rate of 1000 Nm3/h. The NOx concentrations at the boiler outlet were 90-95 ppm. Furthermore, during a 300-min continuous operation when firing 20% mixed oil, a NOx removal efficiency of more than 90% was confirmed. This is equivalent to less than 10 ppm at the scrubber outlet when the flue gas flow rate was 870 Nm3/h. In addition, CO2 reduction when heavy oil was replaced with WVO was estimated. The system comparison is described between the plasma-chemical hybrid NOx removal and the conventional NOx removal.

Unified process assessment for resources use and waste emissions by coal-fired power generation

A unified process assessment is carried out to integrate various resources and emissions associated with the life cycle of typical coal-fired power generation systems, based on the thermodynamic concept of exergy as a common objective measure. For a comprehensive assessment of industrial production systems, three indicators termed as ecological efficiency, resources use efficiency and environmental emission intensity are devised to evaluate the overall efficacy. Concretely assessed in the present work are three typical modes of coal-fired power generation systems, i.e., the Average mode that represents the average emissions and efficiency of coal-fired power plants operating in the US in 1999, the New Source Performance Standards (NSPS) mode that meets the New Source Performance Standards, and the low emission boiler system (LEBS) mode as a kind of highly advanced coal-fired power plant utilizing a low emission boiler, as benchmark cases in related NREL (National Renewable Energy Laboratory) report.

Advanced Coal-Fired Power Plants

The U.S. Department of Energy is partnering with industry to develop advanced coal-fired electric power plants that are substantially cleaner, more efficient, and less costly than current plants. Low-emission boiler systems (LEBS) and high-performance power systems (HIPPS) are based, respectively, on the direct firing of pulverized coal and the indirectly fired combined cycle. LEBS uses a low-NOx slagging combustion system that has been shown in pilot-scale tests to emit less than 86 g/GJ (0.2 lb/106 Btu) of NOx. Additional NOx removal is provided by a moving bed copper oxide flue gas cleanup system, which also removes 97–99 percent of sulfur oxides. Stack levels of NOx can be reduced to below 9 g/GJ (0.02 lb/106 Btu). Construction of an 80 MWe LEBS proof-of-concept plant is scheduled to begin in the spring of 1999. Engineering development of two different HIPPS configurations is continuing. Recent tests of a radiant air heater, a key component of HIPPS, have indicated the soundness of the design for air temperatures to 1150°C. LEBS and HIPPS applications include both new power plants and repowering/upgrading existing plants.

U-Turn for NOx

DB Riley Inc., Worcester, MA, is developing a low emission boiler system (LEBS) supercritical boiler that integrates advanced low nitrogen oxide coal burners with furnace air staging and coal reburning, and with a proven U-fired slagging furnace configuration. In pilot-scale tests, the new boiler reduced NOx emission to less than 0.2 pound per million Btu on some American coals compared to 0.8 to 1.2 pounds per million Btu from conventional burners. For the US Department of Energy (DOE) LEBS project, DB Riley drew on the related experiences of the advisory board it formed of major utilities, state energy and economic agencies, and research organizations. The DB Riley engineers set a NOx emission limit of 0.2 pound per million Btu for the firing system alone to minimize the amount of NOx to be treated by the post combustion emissions control system. The U-fired design provides sufficient resident time for reburning to effectively reduce NOx.

99/02127 The DB Riley low emission boiler system (LEBS) proof-of-concept (POC) test facility: Beittel, R. et al. Proc. Am. Power Conf., 1998, 60, (1), 179–186

This paper discusses two potential locations for a Proof-of-Concept (POC) Test Facility Design being developed under the US Department of Energy`s Low Emission Boiler System (LEBS) program. The primary goal of the LEBS program is to develop the next generation of pulverized coal-fired power systems to meet stringent emissions requirements with high energy conversion efficiency. The DB Riley team has been chosen to go forward with Phase 4 of the LEBS Program. Phase IV of the program will include the final design and construction of the POC Test Facility. The POC Test Facility plan for the DB Riley Team has been broadened to two potential locations: (1) A greenfield plant at Turris Mine, Elkhart, Illinois and (2) A repowered Cogeneration Steam Plant at the Savannah River Site, Aiken, South Carolina. Testing at existing large-scale experimental facilities is proposed to support either POC site. The Turris Mine location is currently being pursued as the primary site with the Savannah River location being considered as a contingency location. Each POC Facility includes provisions for testing and evaluating two important LEBS technologies: an advanced U-fired low-NO{sub x} slagging combustion system and the copper oxide flue gas cleanup (FGC) process.

99/02139 Status of phase II subsystem testing in support of B&W's advanced coal-fired low-emission boiler system: Mcdonald, D. K. and Devault, D. J. PWR (Am. Soc. Mech. Eng.), 1996, 30 (Proceedings of the International Joint Power Generation Conference, Vol. 2), 285–294

99/02139 Status of phase II subsystem testing in support of B&W's advanced coal-fired low-emission boiler system: Mcdonald, D. K. and Devault, D. J. PWR (Am. Soc. Mech. Eng.), 1996, 30 (Proceedings of the International Joint Power Generation Conference, Vol. 2), 285–294

99/01401 B&W's advanced coal-fired low emission boiler system commercial generating unit and Proof-of-Concept Demonstration : Mcdonald, D. K. and Madden, D. A. PWR (Am. Soc. Mech. Eng.), 1997, 32, (2), 69–77

99/01401 B&W's advanced coal-fired low emission boiler system commercial generating unit and Proof-of-Concept Demonstration : Mcdonald, D. K. and Madden, D. A. PWR (Am. Soc. Mech. Eng.), 1997, 32, (2), 69–77

99/00607 Status and demonstration of the B&W DRB-4Z burner developed for B&W's advanced coal-fired low-emission boiler system

99/00607 Status and demonstration of the B&W DRB-4Z burner developed for B&W's advanced coal-fired low-emission boiler system

97/04843 The worldwide applicability of B&W's advanced coal-fired low-emission boiler system: McDonald, D. K. et al. Proc. Annu. Int. Pittsburgh. Coal Conf., 1996, 13, (1), 147–153

97/04843 The worldwide applicability of B&W's advanced coal-fired low-emission boiler system: McDonald, D. K. et al. Proc. Annu. Int. Pittsburgh. Coal Conf., 1996, 13, (1), 147–153

97/04818 The ABB LEBS system design: Ragan, J. W. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1996, 13, (1), 137–144

The objectives of the U.S. Department of Energy (DOE) {open_quotes}Engineering Development of Advanced Coal-Fired Low-Emission Boiler Systems{close_quotes} (LEBS) project are to dramatically improve environmental performance of future pulverized coal-fired power plants, to increase their efficiency and to reduce their cost of electricity using near-term technologies, i.e., advanced technologies that are partially developed. The overall objective is to expedite commercialization of the technologies that are developed. The paper describes the work by the ABB team on the LEBS project which is part of the DOE`s Combustion 2000 Program. A major deliverable of the Project is the design of a 400 MWe commercial generating unit (CGU). The design being developed by the ABB team is projected to meet all the project objectives and to reduce emissions of NO{sub x}, SO{sub 2} and particulates to one-third to one-sixth NSPS limits while increasing net station efficiency significantly and reducing the cost of electricity. Development activities supporting the design work are described in the paper.

97/03972 10 MW prototype testing of LIDS as part of the Babcock & Wilcox low emission boiler system

97/03972 10 MW prototype testing of LIDS as part of the Babcock & Wilcox low emission boiler system

97/03939 Coal utilization & fuel systems conference, 1994 ‘advanced coal-fired slagging combustor for the low-emission boiler system’

97/03939 Coal utilization & fuel systems conference, 1994 ‘advanced coal-fired slagging combustor for the low-emission boiler system’

97/03947 Development and design of an advanced coal-fired low-emission boiler system

97/03947 Development and design of an advanced coal-fired low-emission boiler system

97/03927 Achieving compliance with advanced coal-fired low-emission boiler systems

The paper reports on ABB`s work in Phase I of the U.S. Department of Energy (DOE) project {open_quote}Engineering Development of Advanced Coal-Fired Low-Emissions Boiler Systems{close_quote} (LEBS) which is part of the DOE`s Combustion 2000 Program. Work planned for fixture Phases is also described. The overall objective of the LEBS Project is to dramatically improve environmental performance of future coal-fired power plants without adversely impacting efficiency or the cost of electricity Near-term technologies, i.e., advanced technologies that are partially developed, will be used to reduce NO{sub x} and SO{sub 2} emissions to one-third current NSPS limits and particulates to one-half current NSPS limits. Air toxics must be in compliance. Waste must be reduced and made more disposable. The work in Phase I included concept development and evaluation of several subsystems for controlling the emission of SO{sub 2}, NO{sub x}, and particulates. Candidate technologies were then evaluated in various combinations as part of complete advanced supercritical power generation systems. One system was selected for preliminary design of a commercial generating plant.

97/03932 B&W's advanced coal-fired low-emission boiler system: Preparation for and preliminary results of subsystem testing

97/03932 B&W's advanced coal-fired low-emission boiler system: Preparation for and preliminary results of subsystem testing

The U.S. Department of Energy's Combustion 2000 program: Clean, efficient electricity from coal

The United States Department of Energy's Pittsburgh Energy Technology Center, under its Combustion 2000 program, is working with private industry to develop two kinds of advanced, coal-fired electric power generation systems that will have significantly higher thermal efficiency, superior environmental performance and a lower cost of electricity than current coal-fired plants. The low emission boiler system (LEBS) is a highly advanced pulverized-coal-fired power plant which will be ready for commercial introduction before the year 2001. LEBS uses supercritical steam conditions and substantial low-level heat recovery to achieve an efficiency of 42%. Very low emissions are realized by using advanced combustion technology and pollution controls that are integrated with the boiler. The high performance power system (HIPPS) is based on indirectly fired combined-cycle technology that is capable of 47–50% efficiency. This system uses a gas turbine driven by a clean air working fluid separately heated in a novel high-temperature furnace. Energy recovered from the turbine exhaust drives a steam cycle. HIPPS is planned to be commercially available by 2005. This paper describes the Combustion 2000 program and the technologies being developed for LEBS and HIPPS.

97/03285 Investigation of the moving-bed copper oxide process for flue gas cleanup

The Moving-Bed Copper Oxide Process is a dry, regenerable sorbent technique that uses supported copper oxide sorbent to simultaneously remove SO{sub 2} and NO{sub x} emissions from flue gas generated by coal combustion. The process can be integrated into the design of advanced power systems, such as the Low-Emission Boiler System (LEBS) or the High-Performance Power System (HIPPS). This flue gas cleanup technique is currently being evaluated in a life-cycle test system (LCTS) with a moving-bed flue gas contactor at DOE`s Pittsburgh Energy Technology Center. An experimental data base being established will be used to verify reported technical and economic advantages, optimize process conditions, provide scaleup information, and validate absorber and regenerator mathematical models. In this communication, the results from several process parametric test series with the LCTS are discussed. The effects of various absorber and regenerator parameters on sorbent performance (e.g., SO{sub 2} removal) were investigated. Sorbent spheres of 1/8-in diameter were used as compared to 1/16-in sized sorbent of a previous study. Also discussed are modifications to the absorber to improve the operability of the LCTS when fly ash is present during coal combustion.

97/01998 Development and design of an advanced pulverized coal-fired system

Under the US Department of Energy (DOE) project `Engineering Development of Advanced Coal-Fired Low-Emission Boiler Systems` (LEBS) the ABB team developed the design of a 400 MWe advanced pulverized coal fired electric generating system. The work and the results are described in the paper. Early work included concept development and evaluation of several subsystems for controlling the emission of SO{sub 2}, NO{sub x}, particulates and for reducing wastes. Candidate technologies were then evaluated in various combinations as part of complete advanced supercritical power generation systems. One system was selected for the design of the advanced generating system. Pilot scale testing is now being conducted to support the design of subsystems. The design meets the overall objective of the LEBS Project by dramatically improving environmental performance of pulverized coal fired power plants without adversely impacting efficiency or the cost of electricity. Advanced technologies will be used to reduce NO{sub x}, SO{sub 2}, and particulate emissions to one-fifth to one-tenth of current NSPS limits. Air toxics will be in compliance, and wastes will be reduced and made more disposable. Net station (HHV) efficiency can be increased to 45 percent without increasing the cost of electricity.

96/06316 Advanced burner design for pulverized coal combustion in utility boilers

As part of the Combustion 2000 Program of the US Department of Energy, advanced low-emission boiler systems are being developed for future coal-fired power plants. These plants will be extremely clean, highly efficient and economic, by employing emerging and state-of-the-art technologies. The emissions of SOx, NOx and particulates from the plants will be much lower than the current new source performance standards (NSPS), and the net plant efficiency of generating electricity will be higher than that of today's pulverized-coal-fired utility plants. The high plant efficiency results in low fuel use and reduced emission of gases (CO2) associated with global warming. At present, engineering development of advanced systems is being conducted by three industry teams. The development work includes new emission control technologies, state-of-the-art boiler designs and low-temperature heat recovery systems for improved plant efficiencies, systems for improved ash disposability and reduced waste generation, and optimum system integration and plant controls. The technologies considered by these teams for low-emission boiler systems are discussed.